Vision system for an automated test system

ABSTRACT

An example test system includes test sites that include sockets for testing devices under test (DUTs), pickers for picking DUTs from the sockets or placing the DUTs in the sockets, and a gantry on which the pickers are mounted. The gantry is configured to move the pickers relative to the test sites to position the pickers for picking the DUTs from the sockets or placing the DUTs into the sockets. The test system also includes one or more LASER range finders mounted on the gantry for movement over the DUTs in the sockets and in conjunction with movement of the pickers. A LASER range finder among the one or more LASER rangefinders mounted on the gantry is configured to detect a distance to a DUT placed into a socket.

TECHNICAL FIELD

This specification relates generally to automated test systems andcomponents thereof.

BACKGROUND

System-level testing (SLT) involves testing an entire device, ratherthan individual components of the device. If the device passes a batteryof system-level tests, it is assumed that the individual components ofthe device are operating properly. SLT has become more prevalent as thecomplexity of, and number of components in, devices have increased. Forexample, a chip-implemented system, such as an application-specificintegrated circuit (ASIC), may be tested on a system level in order todetermine that components that comprise the system are functioningcorrectly.

SUMMARY

An example test system includes packs. The packs include test socketsfor testing devices under test (DUTs) and at least some test electronicsfor performing tests on the DUTs in the test sockets. Different packsare configured to have different configurations. The differentconfigurations include at least different numbers of test socketsarranged at different pitches. The example test system may include oneor more of the following features, either alone or in combination.

The example test system may include pick-and-place automation configuredto move the DUTs into and out of the test sockets. The pick-and-placeautomation may be configured at least to service the packs havingdifferent configurations. The pick-and-place automation may beconfigurable to transport different types of DUTs. The pick-and-placeautomation may be configurable based on test time and throughput.

Each of the packs may be modular and can be moved into and out of—forexample, completely out of—the test system during operation of thepick-and-place automation on test sockets contained on a different pack.A pack may include one or more rows, with each row containing one ormore test sockets. Each test socket may be associated with an actuatorto place a lid over the test socket or to remove the lid from the testsocket. At least two of the rows of a pack may be configurable to holddifferent types of DUTs. One or more of the packs—for example eachpack—may be configured to hold and to test different types of DUTs.

The test system may include a cool atrium that houses the test socketsand that is supplied with cooled air, and a warm atrium arranged toreceive air from the cool atrium that has been warmed as a result oftesting the DUTs. The warm atrium may be one of multiple warm atriums,with each warm atrium being for a different pack. The test system mayinclude an air-to-liquid heat exchanger to produce the cool air fromcirculated warm air from the warm atrium, and one or more fans to movethe cool air into the cool atrium. The test system may include anionized air supply and one or more fans to move ionized air from theionized air supply over at least some of the test sockets. The testsystem may include a thermal control system to independently andasynchronously control a temperature of individual test sockets.

As noted, the pick-and-place automation may be configured to move theDUTs into and out of the test sockets and the pick-and-place automationmay be configured at least to service the different configurations ofthe packs. The pick-and-place automation system may include pickers forpicking DUTs from the test sockets and/or placing the DUTs into the testsockets and a gantry on which the pickers are mounted. The gantry may beconfigured to move the pickers relative to the test sockets to positionthe pickers for picking the DUTs from the test sockets or placing theDUTs into the test sockets. The pickers may be operable independentlyand simultaneously. The pickers and gantry are robotics for the testsystem and may be arranged in a layer above the test sockets The pickersand gantry may be the only robotics for the test system that arearranged in the layer above the test sockets. The test system mayinclude trays having cells for holding at least one of DUTs to be testedor DUTs that have been tested. The pickers may be configured to pick theDUTs to be tested from the trays and to place the DUTs to be tested inthe test sockets, and to pick the DUTs that have been tested from thetest sockets and to place the DUTs that have been tested into the trays.

The test system may include a housing in which the pickers and thegantry are mounted and in which the packs are held. A pack may bemovable into or out of the housing during operation of thepick-and-place automation on a different one of the packs. The pickersmay be operable independently in four degrees of freedom. The pickersmay each be operable independently in four degrees of freedom.

Testing performed on the DUTs by the test system may includesystem-level tests. A first one of the packs may include one or moretest sockets and a second one of the packs may include two or more testsockets. The different configurations may accommodate different types ofDUTs in the test system at a same time. The different configurations maysupport different types of DUTs having different form factors in thetest system at a same time. The different configurations may supportdifferent types of DUTs having different electrical interfaces in thetest system at a same time. The different configurations may supportdifferent types of DUTs having different thermal requirements in thetest system at a same time. The different configurations may supportdifferent types of DUTs having different physical interfaces in the testsystem at a same time. The different configurations may supportdifferent types of DUTs having different wireless functionalities in thetest system at a same time. The different configurations may supportdifferent types of DUTs having electro-mechanical interfaces in the testsystem at a same time.

An example test system includes a test socket for testing a DUT, a lidfor the test socket, and an actuator configured to force the lid ontothe test socket and to remove the lid from the test socket. The actuatorincludes an upper arm to move the lid, an attachment mechanism connectedto the upper arm to contact the lid, where the attachment mechanism isconfigured to allow the lid to float relative to the test socket toenable alignment between the lid and the test socket, and a lower arm toanchor the actuator to a board containing the test socket. The actuatoris configured to move the upper arm linearly towards and away from thetest socket and to rotate the upper arm towards and away from the testsocket. The example test system may include one or more of the followingfeatures, either alone or in combination.

The attachment mechanism may include one or more springs between theupper arm and the lid and a gimbal connected to the upper arm andarranged to contact a stop plate that connects to the lid and thatlimits movement of the lid. The lid may be, or be part of, a lidassembly that includes alignment pins to align the lid assembly tocomplementary holes associated with the test socket. The lid assemblymay include a cap to contact the DUT, a thermoelectric cooler (TEC) incontact with the cap, a thermally-conductive plate in contact with theTEC, and the stop plate in contact with the thermally-conductive plate.The stop plate may be configured to make contact with a frame of thetest socket when the actuator forces the lid onto the test socket.

The lid assembly may include a coolant line to bring liquid coolant tothe thermally-conductive plate and a spring between the stop plate andthe thermally-conductive plate. The lid assembly may include one or moreheaters thermally connected to the thermally-conductive plate. The oneor more heaters may be controllable to increase in temperature. The testsystem may also include a first temperature sensor at the cap to detecta temperature proximate to the DUT and a second temperature sensor atthe cap to detect a temperature at the cap that is farther away from theDUT than the temperature detected by the first temperature sensor.

The upper arm may be part of an assembly that includes cable grommets tohold conduits that route at least one of electrical signals or liquidcoolant to and from the lid.

The attachment mechanism may be configured to allow the lid to float inmultiple degrees of freedom—for example, using the gimbal and spring. Inexamples, the attachment mechanism may be configured to allow the lid tofloat in at least three degrees of freedom, the attachment mechanism maybe configured to allow the lid to float in at least four degrees offreedom, the attachment mechanism may be configured to allow the lid tofloat in at least five degrees of freedom, or the attachment mechanismmay be configured to allow the lid to float in six degrees of freedom.During float, the attachment mechanism may be configured to allow thelid to move in a single dimension by an amount measured in triple-digitmicrons (single-digit millimeters) or less.

The lid may include a lid assembly. The lid assembly may include a TECin thermal communication with the DUT, a thermally-conductive structurein contact with the TEC, and a stop structure such as the stop plate incontact with the thermally-conductive structure. The stop structure isconfigured to make contact with the frame of the test socket when theactuator forces the lid onto the test socket.

The test system may include an enclosure around the test socket. Theenclosure may have an opening to allow the actuator to force the lidonto the test socket and to remove the lid from the test socket. Theactuator may be configured to hold a cover to close the opening tohermetically seal the enclosure and to thermally isolate the enclosurewhen the opening is closed or plugged by the cover. The actuator may beconfigured to move the cover over the opening when the actuator forcesthe lid onto the test socket. The enclosure may include a port that isconnectable to a vacuum source or to a gas source. The test socket mayinclude one or more fins that extend upward and/or downward from thetest socket for heat dissipation.

An example test system may include a test socket for testing a DUT, alid for the test socket, and an actuator configured to force the lidonto the test socket and to remove the lid from the test socket. Theactuator includes an upper arm to hold the lid and a lower arm to anchorthe actuator to a board containing the test socket. The actuator iscontrollable based on proper placement of the DUT in the test socket torotate the upper arm toward the test socket and to force the upper armholding the lid towards the test socket in order to force the lid ontothe test socket and against the DUT in the test socket.

An example method of placing a lid on a test socket of a test systemincludes the following operations: roughly aligning the lid and the testsocket; following rough alignment, finely aligning the lid to the testsocket by moving a cap of the lid over a complementary portion of thetest socket containing a DUT; moving the lid downward into the testsocket so that the cap contacts the DUT while the lid floats relative tothe test socket, where floating includes multi-dimensional movement ofthe lid relative to the test socket; continuing to move the lid downwardthereby forcing the lid against the DUT until a stop plate preventsfurther movement; and retaining the lid forced against the test socketduring testing of the DUT by the test system. The example method mayinclude one or more of the following features, either alone or incombination.

Roughly aligning may include rotating the lid into position over thetest socket such that alignment pins associated with the lid align tocorresponding alignment sockets on the test socket. Finely aligning mayinclude adjusting a position the lid so that the lid is properly alignedto at least one of the DUT or the test socket.

An example test system includes test sites that include test sockets fortesting DUTs and pickers for picking DUTs from the test sockets and/orfor placing the DUTs into the test sockets. Each picker may include apicker head for holding a DUT. The test system also includes a gantry onwhich the pickers are mounted. The gantry may be configured to move thepickers relative to the test sites to position the pickers for pickingthe DUTs from the test sockets or placing the DUTs into the testsockets. The test sockets are arranged in at least one array that isaccessible to the pickers on the gantry. The example test system mayinclude one or more of the following features, either alone or incombination.

The gantry may include a beam that spans across the at least one arrayof test sockets and that is configured to move over the at least onearray of test sockets in a direction perpendicular to the beam. Thepickers may be arranged linearly along the beam and may be configured tomove linearly along the beam. The pickers may be controllable to movelinearly along the beam to change a pitch of the pickers along the beam.The pickers may be controllable to move linearly along the beam tochange the pitch while the beam moves over the at least one array oftest sockets in the direction perpendicular to the beam.

The test system may include packs that include the test sockets and atleast some test electronics for performing tests on the DUTs in the testsockets. Different packs are configurable to have differentconfigurations. The different configurations may include at leastdifferent numbers of test sockets arranged at different pitches. Thepickers may be controllable to move linearly along the beam to changethe pitch to match pitches of different sets of test sockets indifferent packs installed in the test system. The pickers may beconfigured to service multiple test sockets simultaneously, whereservicing may include at least one of placing DUTs into the multipletest sockets or picking DUTs from the multiple test sockets. One or moreof the pickers may be configured, through servo-control, to move atleast partly perpendicularly or obliquely relative to the beam in orderto finely align with one or more respective test sockets. Such movementis referred to as the Y-axis jog, as described herein.

The test system may include one or more temperature sensors configuredto sense a temperature of at least one of the gantry or the test socketsand a control system that is servo-based to change a position of one ormore of the pickers to compensate for thermal expansion of at least oneof the gantry or the test sockets. The test system may include anencoder scale attached to a frame such as a force frame of the testsystem, and an encoder reader attached to the gantry. The control systemis configured to identify vibrations in the test system based on anoutput of the encoder reader and to control operation of the test systemto counteract the vibrations.

As noted, the test system may include packs that include the testsockets and at least some test electronics for performing tests on theDUTs in the test sockets. Different packs are configurable to havedifferent configurations for DUTs having different characteristics. Thepickers are controllable, and a number of the pickers is scalable, basedon characteristics of the packs and/or the test sockets in the packs.

Each picker head may include a nozzle to hold a DUT using at leastvacuum pressure. Examples of nozzles include, but are not limited to, ofthe following: a soft polymer vacuum cup that includeselectrostatic-discharge (ESD) dissipative material, a hard plastic tipthat includes ESD dissipative material, a hard material that includes anintegrated ejection collar to accommodate roll and pitch changes of aDUT, or a soft polymer vacuum cup that includes an integrated ejectioncollar configured to reduce stiction between the nozzle and the DUT.

The test system may include a feeder configured to hold trays havingcells for holding at least some DUTs to be tested or at least some DUTsthat have been tested. The pickers may be configured to pick the DUTs tobe tested from some of the cells and to place the DUTs that have beentested into others of the cells. The trays may be arranged in a planethat is parallel to, or a co-planar with, a plane in which at least some(for example, some or all) of the test sockets are arranged.

The gantry that holds the pickers in the test system may include a firstbeam that spans across the at least one array of test sockets and thatis configured to move relative to the test sockets and a second beamthat spans across the at least one array of test sockets and that isconfigured to move relative to the test sockets. One or more of thepickers may be arranged linearly along the first beam and one or more ofthe pickers may be arranged linearly along the second beam. The gantrythat holds the pickers may be a main gantry and the test system may alsoinclude a LASER cleaning assembly and an auxiliary gantry built onto asame bearing system as the main gantry. The LASER cleaning assembly maybe connected to the auxiliary gantry. The auxiliary gantry may beconfigured to move the LASER cleaning assembly relative to the testsockets in order to clean the test sockets using LASER light.

A pack in the test system may include test sockets and at least sometest electronics for performing tests on the DUTs in the test sockets.The pack may be one of multiple different packs that are installed inthe test system and that support at least one of different types ofDUTs, different configurations of DUTs, different numbers of DUTs, DUTshaving different physical interfaces, DUTs having different electricalinterfaces, DUTs having different form factors, or DUTs having differentsizes. A control system may be configured to control the auxiliarygantry and the LASER cleaning assembly to clean the test sockets whilethe pack is installed in the test system.

The pickers may be controllable to move in three or more degrees offreedom relative to the test sockets. The three or more degrees offreedom may include left-right, forward-backward, up-down, and rotation.The test system may include a machine vision system configured to detectplacement of a DUT in a test socket, a picker holding a DUT, and aconfiguration and orientation of a test socket. The gantry may have asettling time that is at most +/−10 microns in less than 20milliseconds.

The pickers may be or include linear actuators. Each linear actuator maybe configured to extend or to retract a respective picker head. When apicker head is retracted, the picker has sufficient clearance to passover the test sockets including when the test sockets contain DUTs. Eachpicker may be configured for linear movement along part of the gantry toadjust for different center-to-center distances between DUTs in the testsockets or DUTs in trays included in the test system. Linear magneticmotors may be controlled by the control system to position the gantryfor DUT pick-up, placement, and measurement operations. Linear magneticmotors may be controlled by the control system to position the pickersperpendicularly or obliquely to motion of the gantry for DUT pick-up,placement, and measurement operations.

An example test system includes test sites that include sockets fortesting DUTs, pickers for picking DUTs from the sockets or placing theDUTs in the sockets, and a gantry on which the pickers are mounted. Thegantry is configured to move the pickers relative to the test sites toposition the pickers for picking the DUTs from the sockets or forplacing the DUTs into the sockets. The test system also includes one ormore LASER range finders mounted on the gantry for movement over theDUTs in the sockets and in conjunction with movement of the pickers. ALASER range finder among the one or more LASER range finders mounted onthe gantry is configured to detect a distance to a DUT placed into asocket. The example test system may include one or more of the followingfeatures, either alone or in combination.

A control system may be configured to determine a plane of the DUT basedon multiple distances detected by the LASER range finder, and todetermine whether the DUT has been placed properly in the socket basedon the plane of the DUT. The control system may be configured todetermine whether or not to place a lid over the socket based on whetherthe DUT has been placed properly into the socket. The control system maybe configured to control movement of the lid to be placed over thesocket when the DUT has been placed properly in the socket. The controlsystem may be configured to control the lid not to be placed over thesocket when the DUT has been placed improperly in the socket.

The LASER range finder may include a one-dimensional (1D) LASER rangefinder. Each LASER range finder may be mounted on to a respectivepicker. The LASER range finder may be configured to detect distances tothe DUT placed into the socket in parallel with movement of the gantryfollowing placement of the DUT into the socket.

An example test system includes test sites that include sockets fortesting DUTs, pickers for picking DUTs from the sockets or placing theDUTs into the sockets, and a gantry on which the pickers are mounted.The gantry may be configured to move the pickers relative to the socketsto position the pickers for picking the DUTs from the sockets or placingthe DUTs into the sockets. A scanner may be configured to face thesockets and to move over the sockets. The scanner may be configured tocapture three-dimensional data (3D) representing a structure of at leastpart of a socket. A camera may be configured to face the sockets and tomove over the sockets. The scanner or camera may be configured tocapture 3D representing a structure of at least part of a socket. Theexample test system may include one or more of the following features,either alone or in combination.

The example test system may include a control system to determine alocation and an orientation of the socket based on the 3D data. Thecontrol system may be configured to determine a plane of the socket, aroll and pitch of the plane, and a height of the plane relative to abase holding the sockets. The control system may be configured todetermine Cartesian X, Y, and Z coordinates of the plane and a yaw ofthe plane. The control system may be configured to determine theCartesian X, Y, and Z coordinates of the plane and the yaw of the planebased on features associated with the socket. The control system may beconfigured to control a picker to place a DUT into the socket based onthe location and orientation of the socket. The control system may beconfigured to control the picker to place the DUT into the socket at aprecision measured in single-digit microns (μm). The 3D data may includea 3D point cloud.

An example test system includes trays that include cells for holding atleast one of devices to be tested or devices that have been tested,pickers for picking the devices to be tested from the trays and forplacing the devices that have been tested into the trays, and a gantryon which the pickers are mounted. The gantry is configured to move thepickers relative to the cells to position the pickers for picking thedevices to be tested or for placing the devices that have been tested.The test system also includes a scanner configured for movement over thetrays. The scanner may be configured to capture 3D representingstructures of the trays and the presence or absence of devices in atleast some of the cells. A control system is configured to determine,based on the 3D data, which of the cells contains devices and whetherdevices in the cells are placed properly. The example test system mayinclude one or more of the following features, either alone or incombination.

For a tray or each tray, the control system may be configured to performa comparison based on 3D data for the tray and a predefined model of themodel of the tray. For a tray or each, the control system may beconfigured to compare a representation of the tray based on the 3D datato a predefined model of the tray. Determining whether a device in acell is placed properly may include determining whether the device inthe cell is at a prescribed orientation or with an acceptable toleranceof the prescribed orientation. The 3D data may include a 3D point cloud.The scanner may include a 3D scanner mounted on a linear motorized axisover the trays. In some implementations, a 3D camera may replace the 3Dscanner.

An example test system includes test sites that include sockets fortesting DUTs, pickers for picking DUTs from the sockets or placing theDUTs in the sockets, and a gantry on which the pickers are mounted. Thegantry may be configured to move the pickers relative to the sockets toposition the pickers for picking the DUTs from the sockets or forplacing the DUTs into the sockets. The test system may also include ascanner. The scanner may be configured to face towards (e.g., upwardstowards) a DUT held by a picker that is controlled to place the DUT in asocket at a test site. The scanner may be configured to capture 3Drepresenting the picker holding the DUT prior to placement of the DUT inthe socket. A control system is configured to determine, based on the 3Ddata, whether the DUT is properly oriented for placement in the socket.The example test system may include one or more of the followingfeatures, either alone or in combination.

The scanner may include a 3D scanner that is oriented to face upwardstoward a bottom of the DUT. The scanner may be a first scanner and the3D data may be first 3D data. The test system may also include a secondscanner configured for movement over the sockets. The second scanner maybe configured to capture second 3D data representing a structure of atleast part of the socket. The control system may be configured tocontrol the picker to place the DUT into the socket based on the first3D data and the second 3D data. The control system may be configured tocontrol the picker to place the DUT into the socket at a precisionmeasured in single-digit microns (μm), double-digit microns, ortriple-digit microns.

The 3D data may include Cartesian X, Y, and Z coordinates for the DUTbeing held by the picker prior to placement in the socket. The 3D datamay include pitch, yaw, and roll information for the DUT being held bythe picker prior to placement in the socket. The first scanner and/orthe second scanner may be fixed in place.

An example test system includes a strobe light, test sites that includesockets for testing DUTs, pickers for picking DUTs from the socketsand/or placing the DUTs in the sockets, and a gantry on which thepickers are mounted. The gantry may be configured to move the pickersrelative to the sockets to position the pickers for picking the DUTsfrom the sockets or placing the DUTs into the sockets. A camera may beconfigured to face towards a DUT held by a picker controlled to placethe DUT in a socket at the test site. The camera may be configured tocapture an image of the picker holding the DUT prior to placement of theDUT in the socket. A control system may be configured to controloperation of the gantry to reduce a speed of the picker as the pickerapproaches the camera, to control operation of the strobe light and thecamera to capture an image of the picker holding the DUT prior toplacement of the DUT in the socket, and to use the image to determine aposition and an orientation of the DUT relative to the socket. Theexample test system may include one or more of the following features,either alone or in combination.

Controlling the strobe light and the camera may include causing thestrobe light to illuminate at a time that the camera is controlled tocapture the image. The speed of the picker may be reduced to, or changedto, a constant speed. The test system may include a single camera tocapture an image of each picker holding a DUT. The test system mayinclude multiple cameras, each facing an underside of the DUT. Each ofthe multiple cameras may be associated with a different test site andmay be configured to face towards a DUT held by a picker controlled toplace the DUT in a socket. Each camera may be configured to capture animage of the picker holding the DUT prior to placement of the DUT in asocket of the different test site.

An example test system includes test sites that include sockets fortesting DUTs, pickers for picking DUTs from the sockets or placing theDUTs in the sockets, and a gantry on which the pickers are mounted. Thegantry is configured to move the pickers relative to the test sites toposition the pickers for picking the DUTs from the sockets or placingthe DUTs into the sockets. A camera is configured for positioning over asocket using servo control to capture an image of the socket or of adevice in the socket. A control system is configured to implement theservo control of the camera and to use the image to control placing theDUT into the socket or picking the DUT from the socket. The example testsystem may include one or more of the following features, either aloneor in combination.

The camera may include a 3D camera to capture 3D image data representingat least the socket. The 3D camera may include an imaging devicecomprised of two or more lenses that enables perception of depth incaptured images to produce a 3D image. The 3D camera may include atwo-dimensional (2D) camera to capture 2D data of at least the socketand a pointing laser to capture a third dimension of data for at leastthe socket. The 2D data and the third dimension of the data may be the3D image data. The 3D data from the camera may be used by the controlsystem, along with 3D data from one or more of the preceding camerasfacing an underside of the DUT, to control positioning of the DUT in thesocket.

An example test system includes test sites for testing DUTs, where thetest sites include a test site configured to hold a DUT for testing. Thetest system includes a thermal control system to control a temperatureof the DUT separately from control over temperatures of other DUTs inother test sites. The thermal control system includes a TEC and astructure that is thermally conductive. The TEC is in thermalcommunication with the DUT to control the temperature of the DUT bytransferring heat between the DUT and the structure. The example testsystem may include one or more of the following features, either aloneor in combination.

The thermal control system may include liquid coolant to flow throughthe structure to reduce a temperature of the structure. The thermalcontrol system may include one or more conduits to transport the liquidcoolant between the structure and a supply of the liquid coolant and oneor more valves to control a flow of the liquid coolant through the oneor more conduits. The liquid coolant may have a flow to each test sitethat is independently controllable to reduce a temperature of a DUT ineach test site.

The thermal control system may include one or more temperature sensorsto detect a temperature of the DUT and a control system to control thethermal control system based on active feedback of the temperaturedetected at the DUT. The thermal control system may include one or moreheaters in thermal contact with the structure, where the one or moreheaters are operable to increase a temperature of the structure.

The structure may be or include a plate and the thermal control systemmay include conduits to transport the liquid coolant between the plateand a supply of the liquid coolant, a valve along a conduit to control aflow of the liquid coolant through the one or more conduits, and theheaters embedded in the plate. The heaters are operable to increase atemperature of the plate.

The thermal control system may include an enclosure to house the DUT.The enclosure may be configured to enable creation of a thermal paththat allows thermal conductivity between the TEC and the DUT. Theenclosure may physically isolate the DUT from DUTs in other test sites.At least a combination of the liquid coolant and the physical isolationproduced by the enclosure may enable the test system to test the DUTindependently of, and asynchronously from, testing of other DUTs inothers of the test sites. The enclosure may enable indirect contactbetween the TEC and the DUT.

The thermal control system may include a conduit leading from theenclosure to a vacuum source. A valve along the conduit may becontrollable to open to provide vacuum from the vacuum source to theenclosure and may be controllable to close to prevent vacuum from thevacuum source from reaching the enclosure. The thermal control systemmay include a conduit leading from the enclosure to a purge gas source.A valve along the conduit may be controllable to open to provide a gaspurge to the enclosure. The enclosure may be at least partly thermallysealed.

As noted above, the thermal control system may include one or moreconduits to transport the liquid coolant between the structure that isthermally conductive and a source of the liquid coolant. The liquidcoolant may be above a dew point temperature of an environment in thetest system. For example, the liquid coolant may be maintained above adew point temperature of the sealed enclosure.

The test system may include pickers for picking DUTs from the test sitesand for placing the DUTs in the test sites and a gantry on which thepickers are mounted. The gantry may be configured to move the pickersrelative to the test sites and to change a pitch of the pickers duringmovement to match a pitch of the test sites. The test system may includepacks holding electronics for testing groups of the test sites. Thepacks may be movable into and out of the test system (for example,completely out of the test system) during movement of the gantry and thepickers. The test system may include a temperature sensor at the testsite to detect a temperature at a socket of the test site; one or moretemperature sensors on the gantry to detect a temperature at the gantry;and a control system to change a position of one or more of the pickersbased on the temperature at the socket and the temperature at thegantry.

The thermal control systems may include (i) a heater that iscontrollable to heat the structure and (ii) the liquid coolant to flowthrough the structure to reduce a temperature of the structure. The testsystem may include a control system to control the heater to heat thestructure during heated testing of the DUT and, following heatedtesting, to control a flow of the liquid coolant through the structureto cool the structure to a handling temperature. As noted, the liquidcoolant being may be above a dew point temperature of an environment inthe test system. The control system may control a flow of the liquidcoolant through the structure while the TEC conducts heat from the DUTthereby bringing a temperature of the DUT below a predefined temperaturefor testing. One or more of heaters may be controllable to heat thestructure as noted. The control system may be configured to control theone or more heaters to heat the structure at greater than or equal to apredefined rate for testing.

The thermal control system may be configured to control the temperatureof the DUT in a range from below 0° Celsius (C) to at least 150° C.

An example method of controlling a temperature of a device under test(DUT) includes changing a temperature of a plate that is thermallyconductive by controlling an amount of liquid coolant that flows throughthe plate, controlling a temperature of the plate by controllingoperation of heaters in contact with the plate, and controlling a TEC,where the TEC transfers heat between the plate and the DUT to controlthe temperature of the DUT. The method may include one or more of thefollowing features, either alone or in combination.

Controlling the amount of liquid coolant that flows through the platemay include preventing liquid coolant from flowing through the plate.Controlling operation of the heaters may include turning the heaters onto increase a temperature of the plate. The TEC may control thetemperature of the DUT by transferring heat from the plate to the DUT.The operation of the heaters may be controlled to heat the DUT at a ratethat is greater than or equal to a predefined rate.

Controlling the amount of liquid coolant that flows through the platemay include allowing liquid coolant to flow through the plate.Controlling operation of the heaters may include turning the heaters offto reduce or to prevent heating of the plate. The TEC may control thetemperature of the DUT by transferring heat from the DUT to the plate.In an example, the liquid coolant is not below a dew point of anenvironment in a test system which the method is performed. The TEC maytransfer an amount of heat from the DUT to the plate to cause the DUT tobe below a predefined temperature during testing. The DUT may be in anenclosure that is thermally insulated from, and hermetically sealedfrom, other enclosures containing other DUTs. The method may includecontrolling a dew point temperature in a micro-environment within theenclosure and controlling a temperature of the plate so that thetemperature of the plate remains above the dew point temperature in themicro-environment. The temperature of the plate and the dew pointtemperature may change over a range; however, over the entirety of therange, the temperature of the plate remains above the dew pointtemperature.

The heaters may be controlled to heat the structure to implement heatedtesting on the DUT. Following heated testing, the heaters may beturned-off and the liquid coolant may be controlled to flow through thestructure to cool the structure down to a handling temperature.

Any two or more of the features described in this specification,including in this summary section, can be combined to formimplementations not specifically described herein.

The systems, techniques, and processes described herein, or portionsthereof, can be implemented as and/or controlled by a computer programproduct that includes instructions that are stored on one or morenon-transitory machine-readable storage media, and that are executableon one or more processing devices to control (e.g., coordinate) theoperations described herein. The systems, techniques, and processesdescribed herein, or portions thereof, can be implemented as anapparatus, method, or electronic system that can include one or moreprocessing devices and memory to store executable instructions toimplement various operations. The systems, techniques, processes, and/orcomponents described herein may be configured, for example, throughdesign, construction, arrangement, placement, programming, operation,activation, deactivation, and/or control.

The details of one or more implementations are set forth in theaccompanying drawings and the description below. Other features,objects, and advantages will be apparent from the description anddrawings, and from the claims.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an example test system.

FIG. 2 is a perspective view of the example test system absent itshousing to show internal components of the test system.

FIG. 3 is a perspective view of parts of pick-and-place automation thatmay be part of an example test system like that of FIG. 1.

FIGS. 4 through 28 are perspective views of parts of pick-and-placeautomation that may be part of an example test system like that of FIG.1, which are shown at various points in time during an operationalsequence.

FIG. 29 is a top cut-away view of an example test system absent itshousing showing internal components of the test system.

FIG. 30 is a perspective view of the example test system of FIG. 29absent its housing to show internal components of the test system.

FIG. 31 is a perspective view of the example test system of FIG. 30absent its housing to show movement of a pack into or out of the testsystem.

FIG. 32 is a perspective view of the example test system of FIG. 30absent its housing to show movement of two opposing packs into or out ofthe test system.

FIG. 33 includes a perspective view of the example test system of FIG.30 absent its housing to show movement of two adjacent packs into or outof the test system, and also includes a perspective view of example packelectronics.

FIG. 34 is a top view of an example arrangement of test sockets on apack.

FIG. 35 is a top view of an example arrangement of test sockets on apack.

FIG. 36 is a front perspective view of the example test system of FIG.29 absent its housing and in combination with a service module.

FIG. 37 is a back perspective view of the example test system of FIG. 37absent its housing and with electronics in the service module exposed.

FIG. 38 is a perspective view of an example picker.

FIG. 39 is perspective view of an example camera and an example picker.

FIG. 40 is a perspective view of an example group of pickers and acamera mounted on a gantry beam of an automated gantry in a test system.

FIG. 41 is a block diagram of an example up-pointing LASER scanningsystem for scanning the underside of devices held by pickers duringtransport through a test system.

FIG. 42 is a block diagram of an example up-pointing camera system forcapturing images of the underside of devices held by pickers duringtransport through a test system.

FIG. 43 is a block diagram of an example one-dimensional LASER rangefinder scanning a device to obtain data used to determine the device'sposition in a test socket.

FIG. 44 is a top view showing example scan locations of aone-dimensional LASER range finder on a device in a test socket.

FIG. 45 is a perspective view of an example test socket containing twothrough-socket LASER beams for determining device presence and position.

FIG. 46 is a block diagram of an example LASER scanning system forscanning device trays.

FIG. 47 is a perspective view of an example in-situ test socket LASERcleaning system that may be include in the test systems describedherein.

FIG. 48 is a perspective view of components of an example test siteincluding an actuator and a lid, with the actuator moved away to exposethe test site.

FIGS. 49 and 50 are perspective and side views, respectively, ofcomponents of an example test site including an actuator and a lid, withthe actuator holding the lid on the test socket.

FIG. 51 is a perspective view of components of an example test siteincluding an actuator and a lid, with the actuator not yet havingapplied the lid to the test socket.

FIG. 52 is a cut-away side view of a test socket lid, an attachmentmechanism to the test socket lid, and part of the actuator's upper arm.

FIGS. 53 to 57 are cut-away side views showing a sequence of operationsperformed by the actuator to place and hold a lid on a test socket.

FIG. 58 is a front perspective view of the actuator showing routings forcable and cooling lines to and from the actuator.

FIG. 59 is a back perspective view of the actuator showing routings forcable and cooling lines to and from the actuator.

FIG. 60 is a cut-away side view of the lid and part of the test socketshowing routing of electrical wiring to temperature sensors on the lid'scap.

FIG. 61 is a perspective view of an actuator and a test socketcontaining an enclosure for physically isolating and thermallyinsulating the test socket during testing.

FIG. 62 is perspective view of a component of the test socket fordissipating heat.

FIG. 63 is cut-away side view of an example test system of the typedescribed herein containing warm and cold atriums and showing air flowbetween the two.

FIG. 64 is a block diagram of components of an example thermal controlsystem for a test site that supports independent and asynchronoustesting.

FIG. 65 is a block diagram of components of an example thermal controlsystem for a test site that supports independent and asynchronoustesting.

FIG. 66 is a perspective view of parts of pick-and-place automation thatmay be part of an example test system described herein and that includestwo movable gantry beams.

Like reference numerals in different figures indicate like elements.

DETAILED DESCRIPTION

Described herein are example implementations of a test system andcomponents thereof. In some implementations, the test system isconstrained in size, without sacrificing speed or throughput. However,the example test system described herein is not limited to anyparticular size, testing speed, or throughput. In some implementations,the test system is an SLT system; however, the components and featuresdescribed herein may be implemented in any appropriate testing context.As noted, SLT involves testing an entire device, rather than individualcomponents of the device. If the device passes a battery of system-leveltests, it is assumed that the individual components of the device areoperating properly. An overview of an example test system is providedfollowed by more in-depth descriptions of the various components of thetest system introduced in the overview.

The example test system includes multiple subsystems. In this regard,the test system includes a frame that holds an automated gantry andprimary pick-and-place automation. A tray feeder contains automation tomove trays that hold devices to be tested and/or devices that have beentested into and out of the system. Packs that are movable into and outof the frame contain test electronics for testing devices held in testsockets. The packs may be movable into and out of the system duringdevice testing. An example pack includes electrical test supportinfrastructure and at least one liquid-to-air heat exchanger. In someimplementations, the liquid-to-air heat exchanger may be omitted from,or external to, the pack. An example pack contains one or more rows oftest sockets, which are part of test sites in the test system and whichhold devices under test (DUT). The test sites may each contain anend-user's test site board. The end-user's test site board contains thetest socket that holds the DUT in some implementations. Each row in apack can contain N customer test sites, where N is an integer betweenone and however many sites can fit in a row based on system size. Eachtest site may include an actuator to hold the DUT in the test socket.The actuator can be replaced as needed and to accommodate a device'sforce requirements.

The example test system also includes a service module that housessystem infrastructure and electronics used for liquid cooling, power,and test computations and other processing. A housing, also referred toas a “skin” or “outer shell”, encloses at least part of the system andholds cool air generated by the system and circulated down across thetest sites and test electronics boards. Additionally, ionized air may becirculated over the test sites before, during, and/or after testing tomitigate electrostatic charge buildup and to reduce or to preventelectrostatic discharge (ESD) events.

The layout of the example test system may be considered advantageous.For example, the test electronics, customer site electronics, and deviceautomation can be configured in a stack. As a result, the test systemcan be extended to whatever length is required for a testingapplication, which may enable an efficient usage of the automation.Furthermore, the test system may include a single layer ofpick-and-place automation to place DUTs in test sockets and to removethe DUTs from the test sockets. This single layer of pick-and-placeautomation may reduce the need for multiple automation exchanges foundin other test systems, which may improve the test system's reliability.The site-row-pack model also may enhance system configurability andmodularity and may reduce the cost of test and serviceability.

FIG. 1 shows an example implementation of a test system 10 of the typedescribed in the preceding paragraphs. In FIG. 1, four doors includingdoor 9 are opened to expose the array of test sites in the test system.FIG. 2 shows parts of test system 10 absent its housing or “skin”. Asnoted, example test system 10 is modular, which may enable the testsystem to accommodate various testing applications. As shown in FIGS. 1and 2, test system 10 includes a frame 11 and housing 12 that, in thisexample, hold eight packs, including packs 13 a, 13 b, 13 c, and 13 d.As described in more detail below, each pack may be customized fortesting a different type of DUT. The packs may each include multipletest sites for testing DUTs. Each test site may include a test socketfor holding a DUT, an actuator and lid assembly, and one or moresensors. Example implementations of these features are described below.

Different packs may include test sockets that are sized to hold DUTshaving different characteristics, such as different sizes, interfaces,or form factors. For example, the test sockets in one pack 13 a may beconfigured to hold DUTs that have a 10 millimeter (mm) dimension (forexample, length, width, or diagonal) and test sockets in another pack 13b may be configured to hold DUTs having a 6 mm dimension. The testsockets may be organized in one or more rows, each containing one ormore test sockets. In rows that contain more than one test socket, thetest sockets may be arranged at different pitches. A pitch may includethe distance between the centers of two adjacent test sockets. Forexample, the pitch may be the distance between the centers of twoadjacent test sockets. The packs may also include test electronicsconfigured to test DUTs held in the test sockets. The test electronicsmay be customized to test features that are unique to a DUT. The testelectronics may include, but are not limited to, pin electronics,parametric measurement units, programmable logic, and/or amicrocontroller or other processing device(s). The test electronics mayexecute, or be used to implement, one or more test routines on each DUTin a test socket.

Test system 10 includes trays 14. In some implementations, each trayincludes cells for holding devices to be tested or cells for holdingdevices that have been tested. The cells may be sized and shaped to holddevices having different sizes, shapes, or form factors. For example,one tray may be configured to hold devices that have a 10 mm dimensionand another tray may be configured to hold devices having a 6 mmdimension. In some implementations, there may be two or more trays foreach different type of device being tested—for example, one traycontaining devices to be tested and one tray containing devices thathave been tested, or one tray containing devices to be tested, one traycontaining devices that have passed testing, and one tray containingdevices that have failed testing. In the example of FIG. 1, there aresix trays; however, any appropriate number of trays may be included inthe test system. As shown in the figure, the trays may be arranged in aplane that is parallel to, or a co-planar with, a plane in which at someor all of the test sockets 15 are arranged.

Test system 10 includes pick-and-place automation, which is alsoreferred to as “pick-and-place robotics”. As shown in FIG. 3,pick-and-place robotics 17 may include linear actuators 19, also called“actuators” or “pickers”. Multiple pickers may be configured to servicemultiple test sockets independently and/or simultaneously orcontemporaneously, where servicing includes at least one of placing DUTsinto the multiple test sockets or picking DUTs from the multiple testsockets. Servicing may also include simultaneously picking or placingDUTs into one or more of the trays, as described in more detail below.In the example of FIG. 3, there are four pickers; however, anyappropriate number of pickers may be used. That number may beconfigurable; for example, one or more pickers may be added to orremoved from test 10 system to accommodate different testing applicationrequirements. In this example, a picker 19 a includes an arm thatextends and retracts relative to the test slots. The arm includes a heador nozzle that holds a DUT during movement between cells in the traysand test sockets in the packs. In some examples, a device is picked-upand held on the nozzle during movement using pneumatics, for example avacuum pressure. In some examples, the device is released by releasingthe vacuum pressure and/or by mechanical mechanisms, as describedherein.

Pickers are mounted on a robotic gantry (“gantry”) 20 that includes amovable gantry beam 21 that spans across an array of test sockets 15,rails 21 over which the gantry beam moves, and one or more motors (notshown) to control such movement. Gantry beam 21 is configured to moveover the test sockets in the directions of arrow 23 (the Y-dimension25), which are arranged in rows that are perpendicular to the gantrybeam. Pickers 19 a to 19 d are arranged linearly along gantry beam 21 sothat the test sockets are accessible to the pickers during systemoperation. The pickers are also configured to move linearly along thegantry beam to move to different locations and to change a pitch of thepickers along the gantry beam to service different types of DUTs.Accordingly, in this example, pickers 19 a to 19 d are configured tomove in the Cartesian X dimension 26 (arrow 27) and gantry beam 21 isconfigured to move in the Cartesian Y dimension 25 (arrow 23). Pickers19 a to 19 d thus move in a single plane that is substantially parallelto a plane or planes containing test sites 15. Pickers 19 a to 19 dmounted to gantry beam 21 move along with the gantry beam and are sizedand operated so that, with their arms extended or retracted, the pickersclear—that is, do not touch—test sockets that are empty or full. Inother words, automation 17 is configured to move anywhere within adefined work area and to pass over all sockets, regardless of the stateof the socket (open or closed). This includes clearance for the pickerswhen they are fully retracted. Linear magnetic motors (“linear motors”),which are not shown in FIG. 3, may control movement of both the gantrybeam and the pickers.

In some implementations, the pickers perform picking or placing intodifferent packs. For example, two packs on opposite sides of the system,such as packs 81 b and 81 d of FIG. 31, can have their rows of testsockets aligned in such a way that the pickers can pick and place someDUTs in one pack and others in the other pack simultaneously. Given thetwo packs facing each other on opposite sides' scenario, the “row”accessible by the pick-and-place robotics becomes the sum of the tworows from these two packs. In an example of six sites per row in onepack, the system-level row has 12 sites. The “Y-axis jog” capabilitydescribed below may be particularly useful partly because the rows ontwo opposing packs facing each other may not be perfectly aligned due tovarious tolerances. The Y-axis job capability—which allows forindependent Y-axis movement of the pickers relative to the gantrybeam—allows the test system to accommodate for a misalignment of therows, thereby enabling the system to continue to perform simultaneouspick and place operations.

FIGS. 4 to 28 show a sequence of operations performed by an example testsystem 30 of the type described with respect to FIGS. 1 to 3 in thepreceding paragraphs. The operational positions depicted are random butsequential and are intended to illustrate test system operation. Theparticular operations depicted are not intended to imply any requiredoperations or sequence of operations.

In FIG. 4, pickers 31 are moved by gantry beam 32 into position overtray 34 containing devices to be tested (“DUTs”). More specifically, inthis example, pickers 31 are controlled to move linearly along gantrybeam 32 and the gantry beam is controlled to move linearly along tracks35 to position pickers 31 at tray 24. One or more linear motors (notshown), which are controlled by a control system described below, may beoperated to position the gantry beam and the pickers.

In this example, there are six pickers 31. The six pickers 31 maypick-up or remove six devices or fewer than six devices from tray 34concurrently or in parallel. In some examples, each picker picks-up asingle device; however, not every picker need pick-up a device. As shownin FIGS. 5 and 6, six picked-up devices are transported across one ormore arrays of test sockets 37 in the direction of arrow 38 to targettest sockets 40 in which the device are to be placed. As shown in FIGS.5 to 6, the pitch of the pickers 31 along gantry beam 32 is controlledto change to match the pitch of the target test sockets 40. This changemay be fluid in that pickers 32 may be controlled to move linearly alonggantry beam 32 in the directions of arrow 41 while—for example, at thesame time as—gantry beam 38 is controlled to move along tracks 35.

As described in more detail below, each test socket includes a lidconfigured—for example, constructed, controlled and/or arranged—to fitover the test socket when a device (a DUT) is placed in the test socket.In example implementations, the lid rotates away from a test socket toexpose the test socket and/or a device in the test socket and therebyallow a picker to place a device into the test socket or to remove adevice from the test socket. After a device has been placed in the testsocket, the lid is controlled to move over the test socket and to applya force to the device in the test socket that creates, maintains, orboth creates and maintains electrical and mechanical connection betweenthe device and the test socket. For example, in FIG. 6 the lids of testsocket 40 are open—for example, rotated and/or moved to expose each testsocket—to allow pickers 31 to place the devices they are holding intorespective test sockets 40. In some implementations, lids of the testsockets may be controlled to open during gantry movement towards thetest sockets and may be controlled to close during gantry movement awayfrom the test sockets. In some implementations, lids of the test socketsmay be controlled to open independently of—for example, notduring—gantry movement towards the test sockets and may be controlled toclose independently of—for example, not during—during gantry movementaway from the test sockets.

In FIG. 7, after the pickers place the devices into test sockets 40, thelids of those test sockets close over the test sockets. This movement isrepresented in FIG. 7 by the slightly angled lids 43 moving into placeover test sockets 40. Meanwhile, pickers 31 and gantry beam 32 arecontrolled to move to a row of test sockets 44 to pick-up (that is, toremove) devices that have been tested from those test sockets and thento transfer those devices that have been tested to tray 45. Thistransport is shown in FIGS. 8 and 9. As shown, the pitch of pickers 31is controlled to change from a pitch that is the same as, or approximateto, a pitch of test sockets 44 to a pitch that is the same as orapproximate to a pitch of cells in tray 45. As explained above, thischange may be fluid in that pickers 31 may be controlled to movelinearly along gantry beam 32 in the direction of arrow 48 duringmovement of gantry beam 32 along tracks 35 in the direction of arrow 49.Pickers 31 may place or deposit the devices that have been tested intorespective cells in tray 45 by releasing vacuum pressure, using themechanical mechanisms described herein, or a combination of the two.

As shown in FIG. 10, pickers 31 and gantry beam 32 are next controlledto move so that the pickers align to a new row of cells in tray 34containing devices to be tested. Pickers 31 pick-up the devices in thatrow as described herein and, with gantry beam 32, transport thosedevices to test sockets 50, as shown in FIGS. 11 and 12. In FIG. 12,lids 51 of test sockets 50 are opened to allow the pickers to place thedevices to be tested into the test sockets. As shown in FIG. 13, afteror while pickers 31 and/or gantry beam 32 are controlled to move awayfrom test sockets 50 to next destination test sockets, lids 51 arecontrolled to close to cover devices in test sockets 30.

In FIG. 13, pickers 31 are controlled to pick-up devices that have beentested from test sockets 53. Those devices that have tested are movedto, and placed into, cells on tray 45. As described above, the pitch ofpickers 31 is controlled to change—in this example, to narrow—from apitch equal to or approximate to a pitch of test sockets 53 to a pitchthat is equal or approximate to a pitch of the cells of tray 45 in orderto place the devices that have been tested into the cells.

As shown in FIG. 14, pickers 31 are then controlled move from tray 45 totray 34 in order to pick-up devices to be tested from tray 34 and totransport those devices to test sockets for testing. Specifically,pickers 31 are controlled to move linearly in the direction of arrow 56and gantry beam 32 is controlled to move linearly in the direction ofarrow 57 to pick up devices to be tested from tray 34. Pickers 31 arepositioned as shown in FIG. 15 to pick up devices to be tested from tray34. Then, both pickers 31 and gantry beam 32 are controlled to move tothe position shown in FIG. 16 to place those devices from tray 34 intoempty test sockets 53 (which were evacuated in the operations describedwith respect to FIG. 13). As shown, the lids of those empty test socketsare moved—for example, rotated—out of the way of pickers 31 to exposetest socket 53 and thereby allow pickers 31 to place the devices intothe test sockets for testing. Next, in FIG. 17, lids 59 close overdevices in test sockets 53, while lids 60 over test sockets 61 arecontrolled to open to allow pickers 31 to access, and to pick-up,devices that have been tested from those test sockets 61.

Devices that have been tested are removed from test sockets 61 andplaced into tray 45 as shown in FIG. 18. Pickers 31 and gantry beam 32are then controlled to move linearly to position pickers 31 as shown inFIG. 19 to pick up devices to be tested from tray 34. Pickers 31 andgantry beam 32 are then moved into position to place those devices to betested into test sockets 63. As shown in FIG. 20, the lids 64 of testsockets 63 are moved to expose the test sockets 63 and to enable thepickers to place the devices into test sockets 63. Next, as shown inFIG. 21, pickers 31 and gantry beam 32 are each controlled to movelinearly to position pickers 31 to pick up devices that have been testedfrom test sockets 67 for transport to tray 45. As shown, in FIG. 21, thelids 68 of those test sockets 67 are controlled to open to expose thedevices for pick-up by pickers 31. As shown in FIG. 22, the devices thathave been tested are moved into tray 45 and placed there by pickers 31.Next, in FIG. 23, pickers 31 are moved to tray 34 to pick-up devicesthat have not been tested. That is, pickers 31 and gantry beam 32 areeach controlled to move linearly to position pickers 31 as shown in FIG.23 to pick up devices to be tested from tray 34. Referring next to FIG.24, pickers 31 and gantry beam 32 are controlled to move to place thosedevices to be tested that were picked-up from tray 34 into test sockets70 for testing. Placement is not shown in FIG. 24.

However, as partially depicted in FIG. 24, in this example lids 71rotate in one direction to allow pickers 31 to place devices to betested into respective test sockets 70 and rotate in the oppositedirection to cover the devices after they have been placed, as shown inFIG. 25. Pickers 31 and gantry beam 32 are then controlled to move to anew row 73 to pick-up devices that have been tested from test sockets inthat row and to transport those devices to tray 45. After that, as shownin FIG. 26, pickers 31 and gantry beam 32 are controlled to move thepickers from tray 45 to tray 34 to pick-up devices that have not beentested. As shown in FIG. 27, pickers 31 and gantry beam 32 are thencontrolled to move to place those untested devices into test sockets 73which were previously evacuated as described with respect to FIG. 25.Then, pickers 31 and gantry beam 32 are controlled to move to pick-updevices that have been tested from test sockets 75, as shown in FIG. 28.Operation of the pick-and-place robotics shown in FIGS. 4 to 28 maycontinue in this manner until testing has completed.

In some implementations, a number (for example, six) DUTs to bepicked-up (or locations where DUTs are to be placed) are not in the samerow. As a result, the pickers would not pick or place the DUTsconcurrently or in parallel. Instead, the pickers and the gantry arecontrolled by the control system to perform picking or placing using asmany steps as needed. For example, the pickers and/or the gantry may becontrolled to pick-up two DUTs in parallel on one tray row, then move topick-up four more DUTS in parallel on a different tray row, then move toplace three of those DUTs in parallel into sockets that are aligned inone row, and then move again to place the remaining three DUTs into adifferent set of sockets aligned in another row.

FIGS. 4 to 28 show rows of test sockets having the same pitch. However,as explained previously, the test system may test devices havingdifferent sizes, shapes, and/or form factors in parallel,contemporaneously, and/or concurrently. Accordingly, groups or arrays ofthe test sockets in the same or different packs may have differentpitches but nevertheless share the same pick-and-place robotics and betested by the system in parallel, synchronously, or asynchronously. Thegroups or arrays of the test sockets in the same or different packs maybe tested using the pick-and-place robotics simultaneouslycontemporaneously, or concurrently.

In this regard, as explained with respect to FIGS. 1 and 2, test socketsare held on packs, such as packs 13 a to 13 d, that are movable into andout of frame 12 and housing 11 of test system 10. T summarize, theexample test system incorporates a pack architecture and a modular baseframe. The pick-and-place robotics supports various numbers andconfigurations of packs. The pick-and-place robotics is configured toservice different configurations of the packs. For example, thepick-and-place robotics may be configured to move DUTs into and out ofdifferent types of packs that are installed in the test system at thesame time. In other words, the same automation can be used ondifferently-configured packs. These different types of packs may havetest sockets of different size, height, pitch, and so forth.

In the examples of FIGS. 3 to 28, the pick-and-place robotics arearranged on a horizontal plane in a modular increment within the packarchitecture. The test sockets are installed on a horizontal plane andare arranged in a rectangular array as part of the pack architecture.The number of test sockets in a pack may be based on the size of a DUTto be tested. The number of test sites in a pack may be based on thesize of a test board to be tested. In an example, each pack may containanywhere from one test socket up to 24 test sockets depending on thesize of the test board. However, in other implementations, differentnumbers of test sockets—for example, more than 24 test sockets or fewerthan 24 test sockets—may be included per pack. For example, in someimplementations, a pack may have up to six test sockets or test sites ina row; for example, in some implementations, a pack may have up to eightsix test sockets or test sites in a row; for example, in someimplementations, a pack may have up to ten test sockets or test sites ina row; for example, in some implementations, a pack may have up totwelve six test sockets or test sites in a row; and so forth.

The number of packs to be used may be based on DUT test time and thegantry cycle time to achieve greater tester socket utilization and/orautomation gantry utilization. The pack can be fully removed from theframe, as shown with respect to FIGS. 2 and 31 to 33 described below.Each pack is removable from the frame and passes under the framestructure that supports the gantry. Each pack may be supported on itsown internal wheels. When a pack is removed from the test system, thepack can thus be rolled across a factory floor. The packs may bemechanically aligned to the frame so that when they are removed andreplaced, the sockets will line-up in order to allow the gantry canreach all packs in the same row at the same time.

FIG. 29 shows a top view of components of example test system 80, whichmay be of the type described respect to FIGS. 1 to 28. In this example,test system 80 contains four packs 81 a to 81 d held on rack 82 withinhousing 83. The sockets included in the packs are aligned in rows andcolumns. FIGS. 30 to 32 show perspective views of example test system80. As shown in FIGS. 31 and 32, one or more individual packs such aspacks 81 b and 81 d are removable from the test system. In this example,removable includes fully removable from the test system. Those packs arethen replaceable with the same type of packs or with different packs.Test system 80 is therefore modular in the sense that a pack can bereplaced in the test system in order to test different or the same typesof devices in test sockets on the packs. In this regard, the test systemis configured to operate with or without a full complement of packs.Packs may be replaced without reconfiguring software and/or hardware inthe system. In some implementations, packs can be replaced duringoperation of the pick-and-place robotics in a so-called “hot swap”. Forexample, testing on a pack 81 a may be ongoing while pack 81 b is beingremoved or replaced without interrupted testing on pack 81 a.

FIG. 33 also shows components of test system 80. In particular, FIG. 33shows example electronics 83 that may reside in and/or on each pack,such as pack 81 d. In this example, pack 81 d contains test electronics84, interface electronics 85, a controller board 86, and test sockets87. Interface electronics 85 may include, but is not limited to, amidplane circuit board; standard, semi-custom, or custom customerinterface circuitry; and standard board-to-board internal interfacecircuitry. Test electronics 84 may reside on one or more function boardsthat plug into the midplane. Controller board 86 may include amicroprocessor, microcontroller, or other processing device(s) tocontrol testing performed by the pack and to communicate external to thepack.

As noted, the test sockets may be configured to hold devices that are tobe tested. Different packs may be configured—for example, constructed,arranged, programmed, and/or controlled—to test different types ofdevices. Accordingly, the test sockets may have different configurationsto accommodate different types and/or numbers of devices, to supportdifferent types of devices having different form factors, to supportdifferent types of devices having different electrical interfaces, tosupport different types of devices having different thermalrequirements, to support different types of devices having differentphysical interfaces, to support different types of devices havingdifferent wireless functionalities, and/or to support different types ofdevices having electro-mechanical interfaces. In an example, differentpacks may include, but are not limited to, different numbers of testsockets arranged at different pitches. Furthermore, the test sockets onan individual pack may be configured and/or reconfigured to accommodatedifferent types and/or numbers of devices, to support different types ofdevices having different form factors, to support different types ofdevices having different electrical interfaces, to support differenttypes of devices having different thermal requirements, to supportdifferent types of devices having different physical interfaces, tosupport different types of devices having different wirelessfunctionalities, and/or to support different types of devices havingelectro-mechanical interfaces. Accordingly, arrays or groups of testsockets may differ across different packs or across rows or othersubsections of the same pack.

By way of example, FIGS. 34 and 35 show test sockets in test packsconfigured and/or reconfigured to accommodate different sized devicesfor testing on the test system. In the example of FIG. 34, example testpack 90 is configured to hold test boards (DUTs) that are 130 mm×160 mmin size resulting in a total of 88 test sites containing 88 testsockets. In the example of FIG. 35, example test pack 91 is configuredto hold test boards (DUTs) that are 200 mm×250 mm in size resulting in atotal of 35 test sites containing 35 test sockets.

As noted, the test electronics on a pack may include, but are notlimited to, pin electronics, parametric measurement unit(s),programmable logic, and/or a microcontroller or other processingdevice(s). The test electronics may execute, or be used to implement,one or more test routines on devices in test sockets contained on thepack. In this regard, in some implementations, the test electronics maybe customizable or reconfigurable based on the DUTs to be tested by thepack.

The interface electronics enables connection between a pack and abackplane of the test system. This connection enables communicationbetween the test system and test electronics on the packs. Exampleprotocols that may be supported on the connections include, but are notlimited to, Peripheral Component Interconnect Express (PCIe), UniversalSerial Bus (USB), and the Joint Test Action Group (JTAG) standard.

Referring to FIGS. 36 and 37, example test system 80 may includeelectronics 93 to enable communication between the packs and/or the DUTsand a control system, to provide power to the various packs, and tocontrol servicing and other functionalities, such as LASER (“lightamplification by the stimulated emission of radiation”) scanning, imagecapture, and cleaning described below.

In this regard, test system 80 may include a control system. The controlsystem may include circuitry and/or on-board electronics 93 to controloperations of test-system 80. The circuitry or on-board electronics are“on-board” in the sense that they are located within the housing of thetest system itself. The on-board electronics may include, for example,one or more microcontrollers, one or more microprocessors, programmablelogic such as a field-programmable gate array (FPGA), one orapplication-specific integrated circuits (ASICs), solid state circuitry,or any appropriate combination of two or more of these types ofcircuitry or processing devices.

In some implementations, on-board components of the control systemcommunicate with a remote computing system 95 (FIG. 1), which may bepart of the control system. This computing system is remote in the sensethat it is not located in the housing of the test system. For example,the control system can also include computing resources distributed to aremote location—for example, at a manufacturer's facility—at least aportion of which is not within the test system housing. Connection 94between the test system on-board components and the remote computingsystem may be over a computer network, such as an Ethernet network or awireless network. Commands provide by the remote computing system may betransferred for execution by the on-board electronics. In someimplementations, the control system includes only on-board components.In some implementations, the control system includes a combination ofon-board components and the remote computing system. In someimplementations, the control system may be configured—for exampleprogrammed—to implement control functions based at least in part oninput from a person. Test results and other information generated by thetest system may be stored in computer memory within the housing or theymay be transmitted to the remote computing system.

The control system may include a servo controller or servo controlfunctionality to control the position and velocity of the gantry beamand/or the pickers. An example servo controller may operate to regulatethe velocities and positions of motors controlling the gantry beam andpickers based on feedback signals. In general, a servo controllerexecutes a servo loop to generate a command to minimize an error betweena commanded value and feedback value, such as a commanded velocity andfeedback velocity value. The servo controller may also implementposition control in addition to velocity control. To implement positioncontrol, a position loop may be added in series with the velocity loop.In some implementations, a proportional-integral-derivative (PID)position provides position and velocity control absent a separatevelocity loop.

In some implementations, the control system may be implemented in or bepart of a service module 96, which is shown in FIGS. 29 and 36. In theexample of FIGS. 29 and 36, the service module is connected physicallyto the frame 82 of test system 80; however, that is not a requirement.In some implementations, service module 96 may include test electronicsof the type described herein for performing or assisting in testsperformed on devices in the sockets. Service module 92 may also includeelectronics, such as one or more processing devices, for maintaining thetest system. For example, as described herein, a LASER-based cleaningsystem may be used to clean the test sockets. Electronics to operatethis system may be part of the service module. All or part of thecontrol system described herein may reside in the service module.

As explained previously, devices to be tested and devices that have beentested are stored in trays that are serviced by the pick-and-placerobotics. Example trays that may be used include, but are not limitedto, Joint Electron Device Engineering Council (JEDEC) trays. In theexamples of FIGS. 29 and 37, a feeder 99 is configured to receive traysof tested devices, and to provide trays of untested devices to the testsystem. In an example, the feeder is configured to pass trays into asupport window-frame that promotes tray flatness and to provide arepeatable Z-dimension position of the tray

In the example of test system 10 (FIG. 1), there are six trays (see alsotrays 97 of FIGS. 34 and 35); however, the test systems described hereinare not limited to use with six trays. In the example of test system 30(FIGS. 4 to 28), there are five trays in use; however, the system is notlimited to use with five trays. In a six-tray system, a first tray maycontain untested devices having a first type and a second tray maycontain tested devices having the first type. A third tray may containuntested devices having a second type and a fourth tray may containtested devices having the second type. A fifth tray may contain untesteddevices having a third type and a sixth tray may contain tested deviceshaving the third type. In this example, the first, second, and thirdtypes of devices are different in at least one respect and are testedusing different packs inserted into the test system housing. In someimplementations, different trays may be designated for devices that havepassed testing and for devices that have failed testing. For example,rather than having a single tray for each type of tested device, theremay be two trays for each type of tested device—one tray to hold devicesthat have passed testing and one tray to hold devices that have failedtesting, along with one tray for holding devices of the type that havenot yet been tested. In some implementations, there may be more than onefeeder to move trays into and out of the system and the number of traysmay be different. The feeders may be loaded and unloaded manually orusing automation (not shown) that connects to the test system.

The pickers described herein, such as pickers 31, may include linearmagnetic motors that allow their arms to extend or to retract relativeto a test socket. Each picker may include a picker nozzle that isconfigured to hold a device to be tested or a device that has beentested for transport between the trays and the sockets. In an example,there are six pickers configured to pick-up from one to six devicesconcurrently from a tray or a socket array. In other examples, however,there may be more than six pickers or fewer than six pickers. The numberof pickers in the test system is scalable—for example, one or morepickers may be added to, or removed from, the test system. For example,the number of pickers may be scalable based on characteristics of thepacks and on characteristics of the test sockets in the packs. Forexample, if a pack contains 12 test sockets in a row, the number ofpickers may be a factor of 12. In this regard, the pick-and-placeautomation, such as the number of pickers, can be configured differentlydepending on DUT test time—different DUT types can take different timeto test. Automation configuration does affect maximum throughput in someimplementations. For example, if the automation is configured with morepickers, a maximum number of DUTs that can move through the test systemper hour will be greater.

In some implementations, at least part of each picker is configured tooperate in three degrees of freedom in concert with other pickers in agroup of pickers or independently of the other pickers in the group. Forexample, at least part of each picker may be configured to moveforward-backward (the Y dimension of FIG. 4) independent of and withgantry movement, left-right (the X dimension of FIG. 4), and up-down(the Z dimension of FIG. 4). In the example of FIG. 38, example picker101—which may be of the same type as a picker 19 or 31—includes an arm102 having a nozzle at the end of the arm to hold a DUT. The arm ismovable up-down 103 in the Z-dimension and forward-backward 104 in theY-dimension (which is the Y-axis jog described below). In this example,arm 102 containing the nozzle is also rotatable 105 both in thecounterclockwise direction and in the clockwise direction. This rotationconstitutes movement in a fourth degree of freedom.

In some implementations, an individual picker or each picker in a groupis configured to operate in four degrees of freedom independently of allother pickers. For example, at least part of a picker may be configuredfor independent movement as follows: forward-backward (the Y dimensionof FIG. 4) (the Y-axis jog), left-right (the X dimension of FIG. 4)(movement along the gantry beam), up-down (the Z dimension of FIG. 4)(the picking and placing actions) and, rotation as shown in FIG. 38,which may be used to position DUTs for pick-up, for placement, or forboth.

The pickers are configured to move linearly along the gantry in the Xdimension and to move along with the gantry in the Y-dimension asdescribed previously, for example, with respect to FIGS. 3 to 28.Furthermore, each picker is also configured to move at least partlyperpendicularly or obliquely relative to the gantry beam in order tofinely align with one or more respective test sockets independently ofY-dimension movement produced by the gantry. For example, each pickermay be configured to move in the Y-dimension or partly in theY-dimension to enable parallel or concurrent device pick-up orplacement. This Y-dimension movement may be separate from, andindependent of, movement of other pickers in a group of pickers mountedon a gantry beam. This movement is referred to as “Y-axis jog” as notedabove. Linear magnetic motors may be controlled by the control system toimplement the Y-axis jog movement.

The Y-axis jog capability may accommodate mechanical tolerances in thetest system Y-dimension positions of test sockets in packs and/or ofrows of tray cells. For example, within a row of test sockets,individual devices and/or test sockets may be out of line—for example,off-center relative to other devices and/or test sockets in the row. Forexample, within a row of cells in a tray, individual devices and/orcells may be out of line—for example, off-center relative to otherdevices and/or cells in the row. The deviation in both cases may bemeasured in single-digit microns to single-digit millimeters, forexample. The arms of pickers may be controlled to move in the Y-axis toaccount for such deviations. For example, the arms of the pickers may becontrolled to move each nozzle to a center of its respective targetsocket or DUT to ensure that each picker places its DUT at the center ofthe target socket or picks-up the DUT at its center. The deviations maybe detected by the vision system described herein and the pickers eachmay be controlled individually and independently by the control systemdescribed herein. In an example, the movement in the Y-dimension may beon the order of single-digit microns to single-digit millimeters;however, the Y-axis jog movement is not limited to this numerical range.To reiterate, the Y-axis jog movement of each picker is separate fromY-axis movement of the gantry beam and is relative to the gantry beam.Following DUT placement or pick-up, the Y-axis jog may be used tore-align the pickers during movement of the gantry beam.

As also described herein, individual pickers may be controlled to movealong the gantry beam in the X-dimension to change the pitch between twoor more adjacent pickers. In this regard, in some implementations, eachpicker may be mounted on an individual servo-controlled axis thatenables the picker to dynamically adjust to—for example to matchsubstantially—the center-to-center distance between test sockets and thecenter-to-center distance between tray cells. Examples of this dynamicadjustment are described with respect to FIGS. 4 and 28.

The picker nozzle is mounted on the picker arm, which extends andretracts in the Z-dimension—for example, vertically—as described herein.The picker nozzle is the contact point between the picker assembly andthe DUT. Each nozzle may be configured to hold a DUT using vacuumpressure, for example. The nozzle may be a soft polymer vacuum cupcomprised of ESD-dissipative material, a hard plastic tip comprised ofESD-dissipative material, a hard material comprising an integratedejection collar to accommodate roll and pitch changes of a DUT, or asoft polymer vacuum cup comprising an integrated ejection collarconfigured to reduce stiction between the nozzle and the DUT. Othertypes of nozzles may be used. In some examples, mechanical ejection ofDUT from the nozzle using an injection collar or other appropriate typeof mechanical ejection mechanism may speed throughput and increase theaccuracy at which DUTs are placed in the test sockets.

In some implementations, thermally induced expansion or contraction ofthe gantry beam and/or the test sockets affects positioning of thepickers. For example, the gantry beam may expand in the presence ofexcess heat or contract in the presence of cold, which can cause thepositions of the pickers to change. In an example, the pitch of thepickers and/or the pitch of the test sockets may increase due tothermally induced expansion. In an example, the pitch of the pickersand/or the pitch of the test sockets may decrease due to thermallyinduced contraction. In this regard, in some implementations, one ormore temperature sensors 105 may be attached to the gantry—for example,to gantry beam 21 of FIG. 3. The temperatures sensors may be distributedacross the gantry beam and their values may be averaged or otherwiseprocessed to obtain an estimated temperature of the gantry beam. Thetemperature sensors may detect one or more temperatures of the gantrybeam during operation of the test system and report the temperature(s)to the control system. The control system may execute processes toadjust the servo axes of the pickers in response to the thermallyinduced expansion or contraction of the gantry. For example, the controlsystem may dynamically decrease the pitch of the pickers to counteractthermal expansion or dynamically increase the pitch of the pickers tocounteract thermal contraction. The dynamic adjustment may occur duringtesting—for example, testing is not interrupted and the positions of thepickers is adjusted during gantry beam movement.

In some implementations, one or more temperature sensors may mounted ineach test socket as described herein. The temperatures sensors may bedistributed in any appropriate manner and their values may be averagedor otherwise processed to obtain an estimated temperature of thesockets. The temperature sensors may detect the temperatures of the testsockets during operation of the test system and report the temperaturesto the control system. The control system may execute processes toadjust the servo axes of the pickers in response to the thermallyinduced expansion or contraction of the sockets. For example, thecontrol system may dynamically increase the pitch of the pickers toadjust for thermal expansion of the sockets causing a greater pitchbetween the sockets or dynamically decrease the pitch of the pickers toadjust for thermal contraction reducing pitch between the sockets.

In some implementations, multiple temperature sensors may indicatedifferent amounts of expansion or contraction at different test sockets.In this case, the pitches of individual pickers may be adjustedaccordingly to account for these different amounts of expansion orcontraction. In some implementations, multiple temperature sensors mayindicate different amounts of expansion or contraction at differentpoints along the gantry beam. In this case, the pitches of individualpickers may be adjusted accordingly to counteract these differentamounts of expansion or contraction. For example, in a group of pickers,the pitch between two pickers may be increased while the pitch betweentwo other pickers may be decreased, depending upon circumstances.

In this regard, some or all components of the test system may expand andcontract due to thermal effects. In some implementations, temperaturesare measured at the test sites in the packs as described herein and alsoon the gantry as described above. The control system may be configuredto execute instructions to obtain the temperature data from sensors atthe test sites and at the gantry beam and to process those temperaturesto determine the net thermal expansion and contraction of these twosystems components. The control system may be configured to executeinstructions to make the adjustments to the positions of the pickers toplace DUTs into the test sockets or to pick-up DUTs from the testsockets in a manner that accounts for the relative thermal expansion orcontraction of these and potentially other components of the testsystem. For example, the gantry beam may expand by a first amount andthe sockets may expand by a second amount that is different from thefirst amount. The differences between the amounts of expansion may beused to calculate a net expansion. The control system may use the netexpansion to adjust the pitches between pickers and, in someimplementations, the magnitude of the Y-axis jog. Similar processes maybe performed to account for a net contraction. In some cases, onecomponent may expand and the other component may contract. A netdifference may be determined by the controller based on the amounts ofexpansion and contraction and the resulting net difference may be usedto adjust the positions of the pickers to account for the netdifference. In some implementations, the amount of change in theadjusted pitches between pickers may vary. For example, in the case ofsix pickers, the first two adjacent pickers may have a first net changein pitch, the next two adjacent pickers may have a second net change inpitch, and the third two adjacent pickers may have a third net change inpitch. The first net change, the second net change, and the third netchange may each be different. These different changes may be dictated bydifferent amounts of thermal expansion at different locations.

In some implementations, temperature sensors may be included in thetrays described herein and the control system may be configured toexecute instructions to make the adjustments to the positions of thepickers to place DUTs into the trays or pick-up DUTs from the trays in amanner that accounts for relative thermal expansion and/or contractionof the gantry beam and the trays as described above.

The preceding adjustments to picker positions may be beneficial inexample test system that use one or more down-pointing cameras(described below) to determine the positions of the test sites relativeto the gantry automation including the gantry beam. Some such systemsrely on one or more images captured by one or more down-pointing camerasto determine the positions of the test sites during initial systemsetup. These images may be captured before testing commences. In someimplementations, one or more down-pointing laser scanner may be used inplace of the one or more down-pointing cameras to determine thepositions of the test sites during initial system setup. Because of thehigh throughput of the test system in some examples, a down-pointingcamera may not capture an image every time a DUT is placed in a socket.In some examples, one or more up-pointing cameras capture images takenof every DUT to determine the position of that DUT relative to thepicker. This may be done in real-time for each DUT on a picker, and thisaction may little time. During normal operation of the example testsystem, the control system uses data representing the last knownposition of a test socket captured by the down-pointing camera andstored in memory, and moves the gantry based on that last knownposition. If the temperature of the gantry and/or the temperature oftest socket changes, then the last known position will be wrong. Thetemperature compensation described herein, along with the camerasystems, may ensure, or at least increase the chances that, the pickerwill be accurately positioned for DUT placement operations and for DUTpick-up operations.

In some implementations, temperature compensation may include detectingtemperatures of the test sockets as described herein. The temperaturevalues may be processed—for example averaged—to obtain a value that iscompared to a threshold. In some examples, the temperature values may becompared individually to one or more threshold values and it may bedetermined if a sufficient number of temperature values exceeds athreshold. In either case, if the threshold is exceeded or the number oftemperature values exceeds the threshold, the down-pointing camera(s) orlaser scanner(s) may be controlled to capture new image(s) of the testsockets that have been subjected to the thermal expansion. In the caseof thermal contraction, the control system may determine if theprocessed temperature value is below a threshold or a number ofindividual temperatures is below the threshold. If so, then thedown-pointing camera(s) or laser scanner(s) may be controlled to capturenew image(s) of the test sockets that have been subjected to the thermalcontraction. Testing may be interrupted to capture these new images orthe new images may be captured during testing. These new images may beused to control the position and operation of the gantry beam and thepickers. In examples such as this, the dynamic adjustment of pickerpitch described in the preceding paragraphs may not be performed at all.In some examples such as this, the dynamic adjustment of picker pitchdescribed in the preceding paragraphs may be performed following newimage capture.

As explained previously, the pickers are mounted on gantry. The gantryincludes, among other things, the tracks, the gantry beam that holds thepickers, and one or more motors. The motors may be linear motors thatare configured and controlled by the control system to move the gantrybeam along the tracks as described with respect to FIGS. 4 to 28. Insome implementations, the gantry is a high-speed gantry system directedby machine vision (described below) having coordinated high-speedmovement capability and relatively short settling times. In this regard,the pick-and-place robotics of the example test systems described hereinmay be configured to move a large quantity of DUTs through the testsystem in a relatively short amount of time. This is called “throughput”or Units Per Hour (UPH). In order to achieve targeted throughput andtest times, the pick-and-place robotics may be configured to movequickly and may also be configured to be precise in how they places\ theDUTs into the test sockets. One measure of precision is not just howaccurately the robotics places the device, but also how quickly therobotics can be precise. This “timely precision” is measured using afactor called “settling time”. If the settling time is reduced orminimized, the robotics can perform more actions without waiting for thesystem to settle into its precise position. In this regard, all dynamicsystems vibrate when they move and bounce like a spring when the startand stop. The starting and stopping is achieved through acceleration anddeceleration. When the robotics—for example, the gantry—accelerates ordecelerates, the entire automation structure and base mounting frame mayshake. The servo controller described herein operates to counteract thevibrations caused, for example, by this acceleration or deceleration.The way that the servo controller knows where and when the robot movesor shakes is through use of an encoder device. The encoder deviceincludes an encoder scale and an encoder reader head. The encoder scaleis attached to the frame of the test system, and the encoder reader headis attached to the moving axis of the robotics—for example, the gantrybeam. The encoder head reads the encoder scale to identify vibrations.For example, vibrations can be detected if the encoder head movesrelative to the scale.

If the encoder scale is also shaking due to the vibrations of the frameinduced by acceleration of the robotics, then the servo controller maynot be able to decipher the difference between movements of the roboticsand shaking of the frame. To address this problem, a force frame may beused in the test system. The force frame is a physical mechanism toseparate the mounting of the encoder scale and the robotics' linearmotors. The encoder scale is mounted to a segregated frame (the forceframe) that does not contain motors or robotics. This force frameremains stable even if the frame that holds the motors vibrates. Thismechanical mechanism may improve the settling time of the robot in thatsettling can be addressed by the servo motor even in cases where theframe holding the robotics' linear motors vibrates. The force frame maybe segregated from the main Y-axis of a dual-motor gantry robot has thelargest accelerations and vibrations and has the most impact on thesettling time.

Implementations of the example test system described herein include avision system. An example vision system may include cameras, LASERscanners, or a combination of cameras and LASER scanners of the typedescribed below.

Referring to FIGS. 29, 39, and 40, test system 80 may include a camera107, such as a three-dimensional (3D) camera, that is mounted to gantrybeam 108 via mounting structure 110. In some implementations, the 3Dcamera may be implemented using an imaging device, which may include twoor more lenses, that enables perception of depth in captured images toproduce a 3D image. In some implementations, the 3D camera may beimplemented or approximated using a two-dimensional (2D) camera incombination with a point LASER. In this type of 3D camera, twodimensions (for example, Cartesian X and Y) are captured with the 2Dcamera and depth is captured using the point LASER, an example of whichis the one-dimensional (1D) LASER range finder of FIG. 43. Accordingly,for purposes described herein, a 3D camera may include any electronicsand/or optics that is capable of capturing images having threedimensions, such as length, width, and depth.

Camera 107 is down-pointing, meaning that it is configured to captureimages of surfaces and objects below it. Camera 107 is mounted near agroup of pickers 111 including picker 101, which are also mounted ongantry beam 108. Camera 107 is configured and controllable to movelinearly across the gantry beam along with the pickers. Although onlyone such camera is shown in the figures, the test system may includemore than one such camera. For example, there may be one camera perpicker. Camera 107 may have an adjustable height relative to the gantrybeam. For example, a lens of camera 107 may be movable in theZ-dimension towards or away from the surface that the camera is imaging.Moving the lens or camera farther away from the surface increases itsfield of view, thereby allowing it to capture data over a larger areathan when the lens or camera is moved closer to the surface. Forexample, based on the position of the camera and gantry beam, the cameramay capture images of one or more empty test sockets not covered bytheir lids, one or more occupied test sockets not covered by their lids,or one or more occupied test sockets covered by their lids. For example,based on the position of the camera and the gantry beam, the camera maycapture one or more cells in a tray that do, or do not, hold DUTs.

Image data from camera 107 may be 3D data representing a test socketand, in some cases, a test socket containing a DUT. The 3D contains datarepresenting the X, Y, and Z dimensions. This data is sent by the camerato the control system wirelessly or over one or more system buses. Thecontrol system is configured—for example, programmed—to analyze the datareceived from camera 107. The data may be used to calibrate the cameraand/or to position the pickers. For example, the data may identify alocation of the test socket and/or a location of a device in the testsocket such as when a lid is off the test socket. The control system maycompare this information to expected locations of the test socket and/orthe device, and adjust the locations of the pickers accordingly, eitherthrough movement along the gantry beam or using the Y-axis jog describedpreviously. For example, the data may identify a location of the cell ina tray and/or a location of a device in the cell. The control system maycompare this information to expected locations of the cell and/or thedevice, and adjust the locations of the pickers accordingly, eitherthrough movement along the gantry beam or using the Y-axis jog describedpreviously. The adjustments may be performed in real-time. In thisexample, real-time may be during test operations. Real-time may includeactions that occur on a continuous basis or track each other in time,taking into account delays associated with processing, datatransmission, hardware, and the like.

In some implementations, the vision system includes a 3D LASER scannerthat is down-pointing and that is configured—for example mounted,directed, and/or controlled—to scan across the array of test sockets inthe test system in a manner similar to the LASER scanner described withrespect to FIG. 46. Scanning may be performed on empty test sockets notcovered by their lids, occupied test sockets not covered by their lids,or occupied test sockets covered by their lids. In some implementations,scanning may be performed prior to testing in and the resulting data maybe stored in memory and used to position the pickers as described above.The down-pointing 3D scanner may be mounted on one or more motorizedaxes and may capture 3D data that forms a 3D point cloud representationof the test sockets. In some implementations, a 3D camera may replacethe 3D laser scanner.

This 3D data obtained by the laser scanner or camera may be sent to thecontrol system in the manner described previously. The control systemmay be configured—for example, programmed—to process the 3D data todetermine, for example, the roll and pitch of a single test socket planeas well as a test socket height (Z value). The control system may beconfigured to process the 3D data determine the roll and pitch of aplane containing some or all test sockets and the average height of testsockets in the plane. The control system may be configured to processthe 3D data to determine the X, Y, and Z coordinates of, and yawinformation for, an individual test socket by taking into accountidentifiable features of the test socket such as a 2D array ofspring-loaded connector (e.g., Pogo pin) holes shown in the 3D data. TheX, Y, Z coordinates and yaw information may be used by the controlsystem to control the pickers. For example, the 3D data may identify alocation of the test socket and/or a location of a device in the testsocket when lid is off the test socket. The control system may use suchinformation to control the positions of the pickers, either throughmovement along the gantry beam or using the Y-axis jog describedpreviously. The control system may compare this information to expectedlocations of the test sockets and/or the devices, and adjust thelocations of the pickers accordingly, either through movement along thegantry beam or using the Y-axis jog described previously. In someimplementations, the pickers may be adjusted in this manner during orprior to testing operations.

In some implementations, the preceding 3D scanning may be performedduring pick-and-place operations implemented during system operation. Inthis case, the 3D data from the one or more 3D scanners may be used asdescribed herein to control operations of the pickers in real-time. Insome implementations, the preceding 3D scanning may be performed priorto pick-and-place operations implemented during system operation. Theinformation about test socket and device placement may be used insteadof, or in addition to, the information captured by the 3D camera of FIG.40. For example, the information from the 3D scanner may augment theinformation from the 3D camera or the information from the 3D camera mayaugment the information from the 3D scanner, and the resultinginformation may be used to control the pickers in real-time. Forexample, the information from the 3D scanner and the 3D camera may beaveraged by the control system and the control system may use thisaveraged information to control the pickers in real-time. In someimplementations, one or more 3D scanners may replace the one or more 3Dcameras of FIG. 40. Some implementations may not include down-pointing3D scanners of this type.

The test system may require placement of DUTs into test sockets and/ortray cells at a precision measured in single-digit microns, double-digitmicrons, triple-digit microns, or at any other appropriate precision.Placement at such precisions may require knowledge of how the DUT isbeing held by the picker prior to placement. To this end, the testsystem may include one or more (in this example, two) 3D LASER scanners112, 113 mounted underneath pickers 111 and pointing upwards towardspickers 111, as shown in FIG. 41. The 3D LASER scanners are up-pointingin the example of FIG. 41, meaning that they point upwards towards thebottom of pickers 111 and, therefore, capture the underside of each DUT116 held by the pickers. In FIG. 41, a LASER source scans pickers 111holding the DUTs during movement along gantry beam 108 (X direction 118)and/or during movement of gantry beam 108 (Y direction 119). Theup-pointing 3D LASER scanner(s) may be mounted on fixed brackets and maycapture 3D data that forms a 3D point cloud representation of a DUTbeing held in a picker that itself is mounted on motorized axes. In anexample, the 3D LASER scanners capture 3D data representing X, Y, Zcoordinates and roll, pitch, and yaw information of a DUT being held bythe picker nozzle before the DUT is placed into a test socket. Theresulting data is sent to the control system, which generates a 3D pointcloud based on the data. The control system uses the 3D point cloud,together with information about the locations of the test sockets, tocontrol operation of the pickers to place the DUTs in the test sockets.For example, the control system may use the locations of the testsockets and the DUT X, Y, Z coordinates and roll, pitch, and yawinformation to adjust the locations of the pickers accordingly, eitherthrough movement of the gantry beam, along the gantry beam, or using theY-axis jog described previously. In some implementations, the controlsystem uses the 3D point cloud, together with information about thelocations of the test sockets, to control operation of the pickers toplace the DUTs in tray cells.

The control system may use 3D data from both of the one or moreup-pointing 3D LASER scanners 112, 113 and the one or more down-pointing3D cameras of FIG. 40 to control the gantry and to control the pickersplace DUTs into appropriate test sockets. The control system may use 3Ddata from both the one or more up-pointing 3D LASER scanners 112, 113and the one or more down-pointing 3D LASER scanners to control thegantry and to control the pickers place DUTs into appropriate testsockets. For example, the 3D data from the down-pointing 3D scanners orcameras may represent information about the location, configuration,size, and other attributes of a target test socket, as described herein.The 3D data from the up-pointing 3D scanners may represent informationabout the location and orientation of a DUT on a picker. The controlsystem may receive both sets of 3D data from the two 3D scanners andcontrol placement of the DUT into the target test socket based on thetwo sets of 3D data.

Referring to FIG. 42, in some implementations, test system 80 includesan array 120 of cameras, which may be 3D cameras or 2D cameras, mountedunderneath the pickers 111. The cameras are up-pointing, meaning thatthey point upwards towards the bottom of pickers 111 and, therefore,capture the underside of each DUT such as DUT 116 held by the pickers.Each time the pickers move to place a DUT in a test socket, the gantryand pickers may be moved over the cameras 120 for image capture. In thisexample, strobe lights 121 are mounted on either side of the cameras andpickers. The strobe lights are configured to flash or illuminate atleast the underside of the pickers to enable cameras 120 to captureimages of the DUTs held by the pickers. An example implementation ofcameras 120 and strobe lights 121 is also shown in FIG. 14 and therelated figures, there labeled as cameras 122 and strobe lights 123.Illuminating the underside of the pickers in the manner describedenables cameras 120 to capture images of the DUTs before the DUTS areplaced into the test sockets (or, in some examples, into the trays).Data captured by cameras 120 may be sent to the control system. Thecontrol system is configured to process that data to determine theposition and orientation of a DUT held by the picker or of each DUT heldby each picker. The control system may use the position and orientationof the DUT obtained by the up-pointing cameras in combination with, orindependently of, the data obtained by the up-pointing 3D LASER scannerto adjust the locations of the pickers during placement of DUTs, eitherthrough movement of the gantry beam, movement along the gantry beam, orusing the Y-axis jog described previously. The control system may usethe position and orientation of the DUT obtained by the up-pointingcameras in combination with, or independently of, the data obtained bythe down-pointing 3D LASER scanner(s) to adjust the locations of thepickers during placement of DUTs, either through movement of the gantryor along the gantry beam or using the Y-axis jog described previously.The control system may use the position and orientation of the DUTobtained by the up-pointing cameras in combination with, orindependently of, the data obtained by the down-pointing 3D camera(s) toadjust the locations of the pickers during placement of DUTs, eitherthrough movement of the gantry, movement along the gantry beam, or usingthe Y-axis jog described previously.

Cameras 120 may enable picture taking on-the-fly, for example, inreal-time. For example, after picking a DUT and before placing the DUTinto a test socket, the DUT's precise position and orientation in thepicker may be determined. In order to improve or to maximize throughput,after the DUT has been picked from a tray, the gantry beam may move atfull speed towards the up-pointing cameras 120 but slow down as thegantry approaches the up-pointing cameras. The DUT picker will then moveat a reduced speed and, in some implementations a constant speed, abovethe up-pointing cameras 120. Light from strobe lights 121 captures afreeze-frame of the underside of the DUTs held by the pickers and thecontrol system processes data representing those images to calculate thedesired information.

As noted, strobe lights 121 are arranged and controlled to flash lightwhile pickers holding DUTs are moving at a velocity that is constant orsubstantially constant—for example, less than 1%, 5%, or 10% deviationfrom a prescribed velocity. The number of pickers in the test system maybe based on a desired maximum throughput. Similarly, the up-pointingcameras may vary in number. In some implementations, there may be asingle up-pointing camera. In some implementations, there may be thesame number of up-pointing cameras as the number of pickers, as shown inFIG. 42. In examples where there is only one up-pointing camera, eachpicker holding a DUT is controlled to move in the X-dimension to passover the camera sequentially one-by-one. The strobe lights 121 flash foreach image taken and the camera captures the images sequentially. Inthis case, the gantry to which all of the pickers are attached does notcontinue its travel towards the target sockets until all the images havebeen captured. In the example where there is a same number ofup-pointing cameras as the number of pickers, the cameras operate inparallel to capture all images at the same time and the strobe operatesonce. In some examples, there may be multiple cameras but not one perpicker. In that case, the pickers, the cameras, and the strobe may becontrolled to capture images using a combination of sequential andparallel image captures. By having one up-looking camera for eachpicker, test system throughput can be increased. By contrast, fewercameras may lower the cost of the test system.

All or some of the cameras in the vision system may be positioned onindependent servo axes to expand their depths of field. For example,each camera or its lens may be positioned on an independent servo axisand controlled independently to move towards or away from its target forimage capture—in the examples described herein, that is in theZ-dimension. In this regard, in some implementations, camera and lenscombination used in the test system may have a shallow depth of field.The height of the camera's target can change based on DUT thickness andgeneral variations of a plane containing the test sockets. In order tobring the target into focus, each camera may be mounted on a motorizedaxis that is controllable through servo control to position the camera'slens relative to its target. This type of control also enables thesystem to support DUTs having different heights or thicknesses.

Referring to FIG. 43, to reduce the chances of damage to a DUT or thetest system, the vision system employs one or more 1D LASER rangefinders 125 to determine whether the DUT has been placed properly in thetest socket. Each LASER range finder may be mounted to a picker assemblysuch as picker 101 of FIG. 40 and may operate in the manner describedherein. An example LASER range finder 125 is downward-pointing andcontrollable to direct one or more (in this example, two) LASER beams126, 127 to the DUT 128 in the test socket. Using these LASER beams, theLASER range finder detects a vertical distance from the output of theLASER range finder to a point 130 on DUT 128. The LASER range finder isoperated across a surface of the DUT to detect distances to an array 133of points on DUT 128, as shown in FIG. 44 for example. Data representingthe distance to each point is sent to the control system. The controlsystem processes the data to determine a plane defined by the points.The data may represent an orientation and a position of the plane in 3D(e.g., XYZ) space). The plane constitutes a representation of the planeof the top of the DUT in the test socket. The control system may beconfigured to compare this plane to an expected position of the DUT inthe test socket. The decision of whether or not to press the actuatordown onto the DUT may be altered if the DUT position deviates from anacceptable position by too much. For example, if the result of thecomparison is that the DUT is not in its expected position, or itdeviates from its expected position by more than a predefined amount,such as 1%, 2%, or 3% in any dimension, then the control system maydetermine that the DUT is not positioned properly in the test socket.The control system may then prevent placement of the lid over the testsocket and control the pickers and the gantry to move to the test socketcontaining the DUT, to remove the DUT from the test socket before a lidis placed over the DUT, and to replace the DUT in the test socket. Insome implementation, the DUT may be placed back in a tray. If the resultof the comparison is that the DUT is in its expected position, or itdeviates from its expected position by less than an acceptablepredefined amount, such as 1%, 2%, or 3% in any dimension, then thecontrol system may control placement of a lid over the test socket andforce the lid downwards as described herein. The LASER range finder maybe configured to perform its measurements during approach of the gantryto a target test site or departure of the gantry from the target testsite and, therefore, may not require additional gantry cycle time. Thatis, the LASER range finder may be configured to detect distances to theDUT placed into the socket concurrent to movement of the gantry beforeor after placement of the DUT into the socket.

As indicated above, the LASER range finder makes its determinationbefore a lid is placed over the DUT in the test socket. Furthermore, asnoted, operations performed by the LASER range finder may occur inparallel with—for example, concurrently with or at the same time as—thegantry moves the pickers to a next set of test sockets. Operation inthis manner may result in negligible or no effect on throughput.

Referring to FIG. 45, in some implementations, a test socket 135 of testsystem 80 may include internal LASER beams to detect a position of theDUT in the test socket. For example, test socket 135 may include a fiberoptic sender 136 to output one or more (in this example, two) LASERbeams across the test socket and a fiber optic receiver 135 to receivethe LASER beam(s) output by the fiber optic sender. In this example, thefiber optic sender outputs two different LASER beams 139 and 140 atdifferent heights—for example at 0.35 mm above base 141 of the testsocket and at 0.85 mm above base 141. The fiber optic sender and thefiber optic receiver send data to the control system reporting theiroperational states. If the control system determines that the fiberoptic sender is outputting a LASER beam 139 at 0.35 mm above base 141and that the fiber optic receiver is not receiving that LASER beam, thecontrol system infers that there is a DUT in the socket blocking theLASER beam. The control system thereby determines that the DUT is in thesocket. The different LASER beams may also be used to determine theposition of the DUT in the socket. For example in some implementations,the through-socket LASER beam 140 located at 0.85 mm above base 141 maybe used to detect a DUT that is not in plane with the socket, andtherefore, detect a crooked or misplaced DUT. For example, the controlsystem may know the dimensions of the DUT and the socket. Based on thisinformation, the control system may know that both LASER beams should beblocked by the DUT. If only one LASER beam is blocked—for example, ifthe fiber optic receiver reports receiving LASER beam 140 but not LASERbeam 139—the control system may determine that the DUT is not placedproperly in the test socket. The control system may then control thepickers and the gantry to move to the test socket containing the DUT, toremove the DUT from the test socket before a lid is placed over the DUT,and to replace the DUT in the test socket.

Referring to FIG. 46, in some implementations, the vision systemincludes a 3D LASER scanner 144 that is down-pointing, meaning that itis configured to scan surfaces and objects below it. FIG. 46 shows asingle 3D LASER scanner 144 scanning a single tray 148 in theY-dimension 149; however, the test system may contain multiple such 3Dscanners (for example, one 3D scanner per tray) or a single 3D scannermay scan multiple trays simultaneously. The 3D LASER scanner 144 isconfigured to scan across a tray 148 comprised of cells holding DUTs tobe tested and DUTs that have been tested. The scanning may be performedto determine which cells in the tray contain devices, which do not, andwhether devices are placed properly in their respective cells. Thedown-pointing 3D scanner may be mounted on one or more motorized axesand may capture 3D data that forms a 3D point cloud representation ofthe tray and cells. This data may be sent to the control system in themanner described previously. The control system may be configured—forexample, programmed—to process the 3D data to identify which cells inthe tray contain devices and which do not. For cells in the tray thatcontain devices, the control system may be programmed to determinewhether those devices are correctly positioned, e.g., at a prescribedorientation, in their respective cells. In some implementations, thecontrol system may be configured to determine the roll and pitch of aplane representing some or all of a tray and the average height ofdevices in the tray. The control system may be configured to process the3D data to determine the X, Y, and Z coordinates of, and yaw informationfor, a cell containing a device by taking into account the knownstructure of the cell, such as its four corners. The X, Y, Z coordinatesand yaw information may be used by the control system to control thepickers. For example, the 3D data may identify a location of a tray cellcontaining a device and a position of the device in that cell. Thecontrol system may compare this information to expected locations of thetest socket and/or the device, and adjust the locations of the pickersaccordingly, either through movement of or along the gantry beam orusing the Y-axis jog described previously. In some implementations, thepickers may be adjusted in this manner during or prior to testingoperations. In some implementations, a 3D camera may be substituted for3D LASER scanner 144.

The test system may include a permanently mounted LASER cleaner systemon an auxiliary gantry. For example, as shown in FIG. 47, a LASERcleaning head assembly 159 configured with vacuum debris extraction maybe attached to a separate automated gantry 160 built onto the samebearing system supporting a main gantry beam 161, which may have thesame configuration and operation as gantry beam 21 of FIG. 3 or gantrybeam 32 of FIGS. 4 to 28. The LASER cleaner system is controllable to,and configured to, clean the test sockets inside the test system withoutremoving the test sites or packs from the system frame. The auxiliarygantry and LASER cleaning assembly held thereon may be controlled by thecontrol system and configured to move the LASER cleaning assemblyrelative to the test sockets in order to clean the test sockets usingone or more LASER beams 163. Debris loosened or broken-away by the LASERbeams may be suctioned-up using a vacuum also mounted on the auxiliarygantry. In some examples, cleaning on some test sockets may be performedwhile testing is performed on other test sockets and while the maingantry services test sockets that are not currently being cleaned.

As described previously such as with respect to FIGS. 4 and 28, eachtest site includes a lid that covers a DUT in the test socket and thatholds the DUT in the test socket. Referring to FIGS. 48 to 61, anexample test site includes a lid 166 for the test socket 165 and anactuator 167 configured to force the lid onto, and hold the lid on, thetest socket and to remove the lid from the test socket. Actuator 167includes an upper arm 168 to move the lid; an attachment mechanism 175(see FIG. 52) connected to upper arm 168 to contact lid 166; and a lowerarm 170 to connect and to anchor actuator 167 to a test site circuitboard 171 containing test socket 165.

In an example configuration, the test system includes actuator 167having an upper arm 168 configured to move vertically in the Z-dimensiontowards and away from socket 165. The actuator is configured to move alid onto the test socket and to move the lid off the socket so that thepickers have clear access to the DUT and test socket. A lid assembly orsimply “lid” is configured for the specific socket application in termsof DUT size and thickness, whether the DUT is configured for toptesting, and any DUT-specific heating or cooling requirements Anattachment mechanism, which may be considered part of or separate fromthe lid, includes a stop plate that abuts the socket frame when the lidis full engaged with the test socket to establish a precisionZ-dimension (or vertical) reference. The lid includes springs that arecompressible to provide precise forces to the device in the socket evenif there is fluctuation in force applied by the actuator. The lidincludes a cap that contacts the device. This cap is aligned to thesocket via alignment pins that also align to thermal control componentsin the lid. The thermal components are described in more detail belowand may include passive heat sinks or active components such as a liquidcooled plate, a thermoelectric cooler (TEC), and/or electric heatingelements. The test socket may also include temperature one or moresensors to monitor the temperature of the components. The test socketmay also include one or more temperature sensors to monitor thetemperature of the test socket or the test site containing the testsocket.

The upper arm holds the socket lid. The dimensions of this upper arm canbe configured based on the dimensions of a specific device to test—e.g.,an application board—to provide appropriate reach. Between the upper armand the lid is an attachment mechanism 175 that allows the lid to float,ensuring compliance between the lid and arm and accurate alignmentbetween the lid and test socket. This attachment mechanism may includesprings and centering features so as to return the lid assembly to acenter of its floating range. The upper arm also contains features tosupport any cables or wires required for thermal control components orother test features such as radio frequency (RF) probing to a top of adevice. The lower arm is configured to attach the assembly to anotherstructure, here the customer test site board containing the test socket165. The lower arm also supports an end-user test site board and asupport spider that connects the board to the arm.

As shown in FIG. 48, upper arm 168 is configured and controllable by thecontrol system to rotate away from test socket 165 to expose test socket165 or a device contained therein. This exposure allows a picker toaccess the test socket either to place a device into the test socket fortesting or to pick-up a device from the test socket. After a device hasbeen placed into the test socket 165, upper arm 168 is configured andcontrollable by the control system to rotate towards the test socket toplace lid 166 over the test socket, as shown in FIGS. 49 and 50. Asshown in FIGS. 48 to 50, screw 182 is configured and arranged to enablethe rotation of the upper arm.

Attachment mechanism 175 (FIG. 52) is configured to allow the lid tofloat relative to test socket 165 to enable precision alignment betweenthe lid and the test socket. That is, the attachment mechanism isconfigured to move the lid into contact with the device in the testsocket. The lid floats in the sense that, following contact with thedevice in the test socket, little or no downward pressure is applied tothe lid allowing the lid to move, at least slightly, in one or moredimensions relative to the device in the test socket. For example, thelid may be permitted float in three, four, five, or six degrees offreedom relative to the test socket, where the six degrees of freedominclude forward-backward movement (Y dimension), left-right movement (Xdimension), up-down movement (Z dimension), pitch, yaw, and roll. Insome examples, the amount of movement permitted during floating may bemeasured in single-digit microns, double-digit microns, or triple-digitmicrons (single-digit millimeters); however, other amounts of movementmay be enabled. The floating allows the lid to settle over the testsocket relative to the device therein and may reduce the chances ofdamage when the lid is forced onto the test socket as shown in FIGS. 49and 50. In this regard, in some implementations, upper arm 168 may beconfigured and controllable to rotate slightly following contact betweenthe lid and the test socket to promote settling.

As explained previously, actuator 167 is configured and controllable bythe control system to force the lid into the test socket. That is, afterthe lid is over the device in the test socket and has settled in place,the actuator applies downward force in the Z-dimension in the directionof arrow 184 (FIG. 50) to force the lid onto the test socket so that thelid stays in place and is resistant to movement, during testing. Lowerarm 170 anchors actuator 167 to a circuit board 171 containing testsocket 165, as shown in FIG. 50. Downward force applied by the upper armforces lid 166 onto the test socket and device. There the lid may beheld until testing on the device in the test socket is completed.Afterwards, the lid may be removed to expose the tested device.

FIGS. 51 and 52 show an example configuration of actuator 167 andattachment mechanism 175. More specifically, FIGS. 51 and 52 showactuator 167 including upper arm 168 and lower arm 170. Upper arm 168includes attachment mechanism 175 and lid 166 for placement over testsocket 165. Lower arm 170 anchors the actuator 167 to test site board171. FIG. 52 shows components of an example attachment mechanism 175 andexample lid 166 within the dashed circle. Lid 166 includes a structuresuch as cold plate 190, a TEC 191, and a cap 192. The cap directlycontacts the DUT in the test socket. The cold plate and the TEC are partof a thermal control system for independently and asynchronouslycontrolling the temperature of individual test sockets. A coolantconnection 195 transports liquid coolant to the cooling plate. Thethermal control system is described in more detail below with respect toFIGS. 63 to 65.

Attachment mechanism 175 includes stop plate 196 configured to abut thetest socket frame 220 when the lid is full engaged with the test socketto establish a vertical (or Z-dimension) height reference. The stopplate may be a structure having at least one flat surface in someimplementations. When full force is applied to lid 166, as shown in FIG.57, stop plate 196 contacts the socket frame 220, which prevents orrestricts further downward movement of the lid. Alignment 198 pinsmatch, and fit within, corresponding alignment sockets (that is, holes)on the socket plate. In this example, gimbal 201 is an acorn nutcomprised of a block having a rounded or semi-spherical tip 202 and abody 203 that is polyhedral in this example. The body connects to upperarm 168 and tip 202 contacts stop plate 196. This arrangement allows thelid to tilt freely about the gimbal in multiple dimensions—for example,to float—relative to the test socket prior to the application of fullforce to the lid by the actuator. The lid also contains one or morefloat springs 205 that may be wrapped around corresponding cylindersthat are part of, or that contact, the upper arm or the stop plate. Forexample, float spring 205 is wrapped around a cylinder. Float spring(s)205 enables the lid to float relative to the test socket prior to theapplication of force to the lid by the actuator. For example, the floatspring allows the lid to tilt freely in multiple dimensions relative tothe gimbal while still constraining some motion to maintainconnectivity. Lid 166 also includes one or more cap springs such as capspring 206. Cap spring 206 holds stop plate 196 relative to lid 166 andcompresses when force is applied by the actuator.

FIGS. 53 to 57 show a sequence of operations in which example actuator167 attaches example lid 166 to example test socket 165. In FIG. 53,there is a rough alignment between lid 166 and test socket 165. That is,actuator 157 rotates the lid into position over the test socket suchthat the alignment pins 198 (only one is visible in the figures) alignto, but do not engage, corresponding alignment sockets on test socket165. Actuator 167 thereafter moves the alignment pin toward thealignment socket. Movement of components of the actuator and lid towardthe test socket are shown by dashed arrow 210.

In FIG. 54, lid 166 is finely aligned to the test socket by moving thecap into position over of a complementary portion of the test socketcontaining a DUT and making any rotational adjustments necessary toensure that the lid is properly aligned to the DUT and test socket. Anexample of the complementary portion is within the outline 211 of FIG.45. Actuator 167 begins moving lid downward toward the test socket sothat alignment pin 198 moves into its complementary alignment socket. InFIG. 55, actuator 167 continues to move lid 166 downward and into towardtest socket 165 such that its cap contacts a DUT in the test socket, asshown by dashed arrow 212. In FIG. 56, actuator 167 continues to movelid 166 downward and into test socket 165 forcing gimbal 201 againststop plate 196 and causing float spring 205 and cap spring 206 (FIG. 52)to compress. The lid continues to float to support alignment between thelid and the test socket containing the DUT. The cap is forced furtherinto the test socket as shown by dashed arrow 214. In FIG. 57, actuator167 continues to move lid 166 downward and into test socket 165, asshown by arrow 216. Force applied by actuator 167 against stop plate 196forces stop plate 196 against the test socket frame 220 as shown byarrow 221, thereby preventing further downward movement. At this point,the lid is firmly over the test socket and not movable in any dimension.The lid no longer floats in other words. The lid may be retainedforcibly against the test socket during a duration of DUT testing by thetest system.

To remove lid 166 from the test socket, actuator 167 moves in thedirection of arrow 217, taking lid 166 with it. Actuator 167 may thenrotate upper arm 168 to expose test socket 165 to allow the pickers toaccess a DUT that has been tested.

FIGS. 58 to 60 show examples of cable and coolant paths throughcomponents of actuator 167 and lid 166. FIG. 58 shows cable grommets 190holding electrical wiring 220 to control operation of TEC 191,electrical wiring 221 to control cartridge heaters on the cold plate 190(described below), electrical wiring 222, 223 to communicate with upperand lower temperature sensors, respectively on lid 166, and coolantconduits 224 to circulate coolant to and from cold plate 190. FIG. 59shows a back-perspective view of the actuator and lid shown in FIG. 58.FIG. 58 shows that the length is relatively long and the radius path isrelatively large for the wiring and coolant connections 227 describedwith respect to 58, which produces slack in the wiring and coolantconnections that may reduce stress on the wiring and coolant connectionsduring movement of the actuator. FIG. 60 is a cut-away side view of lid166 showing an example path for electrical wiring 228 to a lowertemperature sensor on lid 166.

Referring to FIG. 61, in some implementations, each test socket includesan enclosure 230 to house a test socket 165 and a DUT in test socket165. The enclosure 230 may provide complete or partial thermalinsulation around the test socket and the DUT in the test socket. Theenclosure 230 may also provide a complete or partial environmental—forexample, a physical or hermetic—seal around the test socket and the DUTin the test socket. The enclosure may be modular and, therefore,removable to support testing with or without the enclosure. Theenclosure is also configured to enable contact between cap 192 and theDUT in the test socket and, therefore, to enable thermalcommunication—for example thermal conduction—between the DUT and the TEC191 and cold plate 190, as described below. That is, in this example,the cap creates a thermal path between the TEC and the DUT. As shown inFIG. 61, enclosure 230 includes a hole or opening 232, through which apicker can pick-and-place a DUT, and through which actuator 167 canplace the test socket lid over the test socket containing the DUT. Anenclosure lid or cover may plug the hole, as described below. In someimplementations, the enclosure may reduce or minimize power usage whenhot and may reduce or prevent condensation when cold.

In some implementations, the control system controls the liquid coolantto keep it at a temperature that is above a dew point temperature of anenvironment containing the test system. The dew point is a temperatureat which air must be cooled to saturate with water vapor. Saturationexists when the air is holding a maximum amount of water vapor possibleat a given temperature and pressure. When the temperature is below thedew point, the water vapor in the air is released as liquid water,namely condensation. Keeping the liquid coolant above the dew pointtemperature may prevent condensation on the coolant transmissionconduits, on the lid, and elsewhere in the test system. Example dewpoints for environmental temperatures include, but are not limited to,indoor air maintained at 20-24.5° C. (68-76° F.) with a 20-60% relativehumidity, equivalent to a dew point of 4.0 to 15.5° C. (39 to 60° F.).

In this regard, an enclosure, such as enclosure 230, creates athermally-insulated and a hermetically-sealed micro-environment aroundits respective test socket. The dew point temperature within thatmicro-environment may be managed, for example, by applying vacuumpressure to the enclosure as described in more detail below. In thisregard, decreasing the atmospheric pressure within enclosure 230 maydecrease the dew point temperature in the micro-environment. In someexamples, dry air may be introduced into the enclosure as described inmore detail below in order to control the dew point within themicro-environment. The rate of flow of, and/or the type of, the liquidcoolant may therefore be controlled—for example, changed or varied—toproduce low temperatures in the micro-environment, such as temperaturesat or below 0° C. (32° F.), while keeping those temperatures above thelowered dew point temperature of the micro-environment. The combinationof managing the dew point temperature in the micro-environment andcontrolling the type and/or flow rate of the liquid coolant to keep thetemperatures produced thereby above the managed dew point temperatureenables low-temperature cooling of the DUT in the test socket whilereducing or preventing condensation on or around the DUT, on or aroundthe test socket, or on or around other components and/or electronicsincluded within the enclosure. In this regard, in some implementations,the thermal control system is configured to control a temperature of aDUT in a test socket in a range from below 0° C. (32° F.) to over 150°C. (302° F.). Other implementations may perform temperature control overdifferent ranges.

Enclosure 230 may be made of metal, composite, or plastic. Enclosure 230may thermally insulate a DUT in test socket 165 from all or some otherDUTs and/or test sockets in the test system. This insulation, combinedwith the thermal control system described with respect to FIGS. 63 to65, enables independent and asynchronous thermal testing of DUTs by thetest system. For example, the test system may perform thermal test onDUTs in different test sockets independently of thermal tests performedon other DUTs in other test sockets. For example, the test system mayperform two different independent and asynchronous thermal tests on twodifferent DUTs in test sockets in the same pack or in the same row inthat pack. For example, the test system may perform two differentindependent and asynchronous thermal tests on two immediately adjacentDUTs; that is, DUTs in two test sockets that are right next to eachother in the same row or column. Also, in connection with the thermalcontrol system described herein, the enclosure enables the test systemto independently and asynchronously control the temperature of eachindividual test socket in the test system. Notably, independent andasynchronous testing is not limited to thermal testing. That is, thetest system may perform any appropriate tests, such as electrical or RFtests, on DUTs in different test sockets independently of andasynchronously from other concurrent tests performed by other DUTs inother test sockets.

Actuator 167 also may hold an enclosure lid 234 that fits over andthermally and physically seals hole 230 when the test socket lid isplaced over the test socket. In some implementations (not shown in thefigures), the bottom half of the enclosure is around the test socket andthe upper arm holds the top half of the enclosure and places it over thebottom half while placing the lid over the test socket. The bottom halfof the enclosure may include the socket frame with a fitting to connectto purge air or vacuum. The top half of the enclosure may be attached tothe cold plate and swing into place with the upper arm. The TEC, thecap, and DUT will be in the enclosure.

In some implementations, enclosure 230 and enclosure lid 234hermetically seal the test socket and DUT contained therein. Forexample, the enclosure and lid may physically isolate the test socketand DUT from all or some other test sockets and DUTs in the test systemand may create an air-tight region around the test socket and DUT. Thisisolation and thermal insulation can prevent contaminants from infectingthe testing operations and enable precise temperature control. A fitting236 may be included on enclosure 230. The fitting may include a port toallow access to the enclosure's interior. For example, vacuum pressureor a gas purge may be applied to the port. A vacuum pressure, or vacuum,may include a pressure that is less than local atmospheric pressure andthat may be defined as a difference between the local atmosphericpressure and a point at which the pressure is measured. The vacuum maysuction air or contaminants from the hermetically-sealed enclosure andmay be used to change the dew point within the enclosure, as describedpreviously. A gas purge may include introducing dry air or nitrogen gasinto the enclosure either before, after, or during testing. In someimplementations, the test system may include one or more supplies ofionized gas, such as ionized air, that may be introduced into theenclosure to reduce to minimize ESD events, as described previously. Insome implementations, one or more fans may be configured and arrangedmove ionized air from the ionized air supply over all or some of thetest sockets while the pick-and-place robots are moving devices into andout of the test sockets and during testing. The ionized air maytherefore also enter the enclosures while the test sockets are exposedduring system operation.

Referring to FIG. 62, in some implementations, test socket 165 mayinclude thermally-conductive fins 238 that extend above and below thetest socket. The fins may be made of metal or any appropriatelythermally conductive material and may facilitate heat dissipation intothe environment from the test socket during testing. The fins may bewithin the enclosure in some implementations.

Referring to FIG. 63, in some implementations, a test system housing 240defines a cool atrium 241 that houses the test sockets and that issupplied with cooled air (represented by arrow 242) and one or more warmatriums 243 arranged to receive air (represented by arrows 244) from thecool atrium that has been warmed as a result of testing the DUTs. In theexample of FIG. 63, there is one different warm atrium for eachdifferent pack; however, that need not be the case. Any appropriatenumber of warm atriums may be included. For example, there may be asingle warm atrium. One or more air ducts 245 may be configured tocirculate the warm air from the warm atriums to an air-to-liquid heatexchanger 247. The air-to-liquid heat exchanger 247 cools the air toproduce the cooled air from the circulated warm air from the atriums.That cooled air may be moved into the cool atrium by one or more fans248. In some implementations, the air circulation system may include oneor more air filters 249 to remove at least some contaminants from thecirculating air.

FIG. 64 shows example components 250 that may be included in a thermalcontrol system for the test systems described herein. The examplethermal control system includes components 253 that are included at eachtest site. Those components may be configured to control a temperatureof a DUT in a test site separately from control over temperatures ofother DUTs in other test sites. The components of FIG. 64 thereforeenable and/or contribute to the test system's ability to control thetemperature of individual test sockets independently and asynchronouslyand, therefore, to perform testing, including thermal testing, on DUTsin the test sockets independently and asynchronously.

In FIG. 64, cold plate 190, TEC 191, and cap 192 may be as describedwith respect to FIG. 52. As shown, TEC 191 is not directly in contactwith a DUT 251, but rather is in indirect contact through cap 192. Cap192 is made of a thermally conductive material such as metal.Accordingly, the indirect contact between the TEC and the DUT throughthe cap still enables thermal conduction between the TEC and the DUT.The cap thus creates a thermal path between the TEC and the DUT. Theresulting thermal conduction enables control over the temperature of theDUT through transfer of heat between the DUT and cold plate 190. Morespecifically, heat is transferred by the TEC between the DUT (throughthe cap) and the cold plate. Operation of the TEC to transfer the heatmay be controlled by the control system. In some implementations, thecap may be left off and the TEC may directly contact the DUT. In suchimplementations, the thermal path will be or include a direct pathbetween the TEC and the DUT.

In this example, cold plate 190 has structure that is at least partlyflat, hence use of the term “plate”. However, cold plate 190 may haveany appropriate structure, including cubical structures or polyhedralstructures. The cold plate may be reduced in temperature using liquidcoolant conduits that run to, through, and/or over the cold plate.Examples of liquid coolant that may be used include, but are not limitedto, chilled water, an ethylene glycol and water mixture,hydrofluoroether (HFE), and silicone oil. One or more conduits 254 areconfigured to transport the liquid coolant between cold plate 190 and asupply 255 of the liquid coolant. The supply may be within the housingof the test system or external to the test system. The liquid coolantthus circulates between the cold plate and its supply. Aliquid/liquid/heat exchanger 257 may be arranged in the circulation pathof the liquid coolant, for example at the supply, to maintain the liquidcoolant at a target temperature using chilled water. A pressureregulator 259 in conjunction with an expansion tank 260 may beconfigured to maintain the pressure of the liquid coolant in theconduits. In some examples, the control system described herein maycontrol the flow of liquid coolant shown in FIG. 64 and controloperation of the liquid/liquid/heat exchanger 257 to maintain thetemperature of the liquid coolant reaching the cold plate at or below68° Fahrenheit (F) (20° Celsius (C)). In some examples, the controlsystem may control these operations to maintain the temperature of thecirculating liquid coolant at different temperatures.

The flow of liquid coolant to each test site is independently andasynchronously controllable to affect—for example, to reduce—atemperature of a DUT in each test site. The control system describedherein may control the flow of liquid coolant to the test site based,for example, on active feedback from temperature sensors at the testsite. The temperature sensors may include a first temperature sensor at,on, or near the cap 192 to detect a temperature proximate to the DUT anda second temperature sensor at, on, or near the cap but farther awayfrom the DUT than the first temperature sensor. Additional or fewertemperature sensors may be used, which may be distributed across variouslocations on the lid. In this example, the two temperature sensors sendtemperature data to the control system. The control system is configuredto control the temperature of the DUT based on the sensed temperaturesbased on the requirements of one or more test programs being run to testthe DUT.

As shown in FIG. 64, thermal control system 250 may include one or morevalves to control a flow of the liquid coolant through the conduits toand from the cold plate 190. For example, valve 262 may be opened toallow coolant to flow to cold plate 190 or closed to prevent coolantfrom flowing to cold plate 190. In some implementations, the valve maybe opened partially or proportionally to regulate the volume of liquidcoolant that is transported to and/or from the cold plate. A greatervolume of liquid coolant provided over a shorter period of time maycause a greater rate of temperature change than a lesser volume ofliquid coolant provided over a longer period of time.

The thermal control system may also include one or more—for exampletwo—heaters 264 embedded in, or placed on, the cold plate. The heatersare adjustable by the control system to increase a temperature of thecold plate and, through conduction via the TEC and the cap, to increasethe temperature of the DUT during testing. The heaters may be arrangedat locations on the cold plate that ensure equal or substantially equaldistribution of heat over the cold plate. This temperature increase maybe a requirement of a test program, for example. During a heating cycle,the flow of liquid coolant to the cold plate may stop or may be reducedso as not to counteract the heating produced by the heaters. The systemmay control the heaters to heat the cold plate at a rate that is greaterthan or equal to a predefined rate required for testing. During coolingusing the liquid coolant, the heaters may be turned off or turned downso as not to counteract the cooling produced by the liquid coolant.

FIG. 65 shows components of the thermal control system in animplementation that includes enclosure 230 of FIG. 61. The othercomponents of FIG. 65 are the same as those labeled also in FIG. 64. Inthis example, at least the combination of the liquid coolant, theheaters, and the physical and thermal isolation produced by enclosure230 enables the test system to test the DUT independently of, andasynchronously from, testing of other DUTs in other test sites. FIG. 65also shows the fitting connected to the enclosure 230 to introducevacuum pressure or purge gas and/or ionized gas into the enclosure. Inthis example, the fitting includes a valve 265 that is controlled by thecontrol system. The valve may be controllable to open to introducevacuum pressure or vacuum—that is, suction—to the enclosure or to closeto prevent vacuum pressure from reaching the enclosure. The valve may becontrollable to open to introduce purge gas to the enclosure or to closeto prevent the purge gas from reaching the enclosure. The valve may becontrollable to open to introduce ionized air from an ionized air supplyto the enclosure or to close to prevent the ionized air from reachingthe enclosure. In some implementations, the purge gas and ionized airmay be mixed and provided to enclosure 230 at the same time.

In operation, the temperature of a DUT in a test socket is controlled bychanging a temperature of cold plate 190 that is thermally conductive.This is done by controlling an amount of liquid coolant that flowsthrough the cold plate and/or controlling a temperature of the coldplate by controlling operation of one or more heaters in contact withthe plate. The TEC is controlled to transfer heat between the plate andthe DUT to control the temperature of the DUT. Following heated testing,the heaters may be turned-off and the liquid coolant may be controlledto flow through the structure to cool the structure down to a handlingtemperature, such as 68° F. (20° C.).

In some implementations of the test system described herein, theautomated gantry may include more than one gantry beam that movesrelative to a horizontal plane of test sites. For example, as shown inFIG. 66, example test system 270 may include two gantry beams 271 and272, each operating as described herein and containing a separate set ofpickers having the features and operability described herein. Duringoperation, gantry beams 271 and 272 may be controlled by control systemso that the two gantry beams access different rows of trays and socketsat the same time or at different times. For example, gantry beam 270 mayaccess front halves of trays 275 and 276 and may service a front half ofthe test sockets and gantry beam 272 (which is in back of gantry beam271) may access back halves of trays 275 and 276 and may service a backhalf of the test sockets. In operation, gantry beams 271 and 272 mayretrieve their devices from the front and back halves of tray 276contemporaneously or concurrently, perform pick and place operations ontheir respective sockets contemporaneously or concurrently, and thenmove back to the feeder contemporaneously or concurrently to deposittested devices in tray 275 and retrieve untested devices from tray 276.In some implementations, the system may include more than two gantrybeams, such as three gantry beams or four gantry beams that each containrespective pickers and that operate in the manner described herein toservice a proportionate share of the test sockets included on thesystem. In some implementations, there may be one gantry beam peropposing pair of packs. In some implementations, each gantry beam may beconfigured to service all sockets in the system, allowing one or more ofthe additional gantry beams to become inoperable without preventing thesystem from testing across the whole work area. The other features oftest system 270 may be as described herein with respect to FIGS. 1 to65.

In example implementations, the test system is 1.6 meters (m) in widthby 8 m in length. However, the test system is not limited to thesedimensions and may be any appropriate size. The test system may scale toaccommodate a user's needs.

In some implementations, individual packs may operate as stand-alonetesters. For example, test sockets of a pack may be manually loaded withDUTs. The pack may then perform one or more test routines on the DUTusing the test electronics contained on the packs. In thisconfiguration, a stand-alone pack may, or may not, communicate with aremote computing or control system to direct testing, to controltesting, and/or to report test results. Upon completion of testing, theDUTs may be manually removed from the test socket and the process may berepeated.

The example test systems described herein may be implemented by, and/orcontrolled using, one or more computer systems comprising hardware or acombination of hardware and software. For example, a system like theones described herein may include various controllers and/or processingdevices located at various points in the system to control operation ofthe automated elements. A central computer may coordinate operationamong the various controllers or processing devices. The centralcomputer, controllers, and processing devices may execute varioussoftware routines to effect control and coordination of the variousautomated elements.

The example systems described herein can be controlled, at least inpart, using one or more computer program products, e.g., one or morecomputer program tangibly embodied in one or more information carriers,such as one or more non-transitory machine-readable media, for executionby, or to control the operation of, one or more data processingapparatus, e.g., a programmable processor, a computer, multiplecomputers, and/or programmable logic components.

A computer program can be written in any form of programming language,including compiled or interpreted languages, and it can be deployed inany form, including as a stand-alone program or as a module, component,subroutine, or other unit suitable for use in a computing environment. Acomputer program can be deployed to be executed on one computer or onmultiple computers at one site or distributed across multiple sites andinterconnected by a network.

Actions associated with implementing all or part of the testing can beperformed by one or more programmable processors executing one or morecomputer programs to perform the functions described herein. All or partof the testing can be implemented using special purpose logic circuitry,e.g., an FPGA (field programmable gate array) and/or an ASIC(application-specific integrated circuit).

Processors suitable for the execution of a computer program include, byway of example, both general and special purpose microprocessors, andany one or more processors of any kind of digital computer. Generally, aprocessor will receive instructions and data from a read-only storagearea or a random access storage area or both. Elements of a computer(including a server) include one or more processors for executinginstructions and one or more storage area devices for storinginstructions and data. Generally, a computer will also include, or beoperatively coupled to receive data from, or transfer data to, or both,one or more machine-readable storage media, such as mass storage devicesfor storing data, e.g., magnetic, magneto-optical disks, or opticaldisks. Machine-readable storage media suitable for embodying computerprogram instructions and data include all forms of non-volatile storagearea, including by way of example, semiconductor storage area devices,e.g., EPROM, EEPROM, and flash storage area devices; magnetic disks,e.g., internal hard disks or removable disks; magneto-optical disks; andCD-ROM and DVD-ROM disks.

Any “electrical connection” as used herein may include a direct physicalconnection or a wired or wireless connection that includes or does notinclude intervening components but that nevertheless allows electricalsignals to flow between connected components. Any “connection” involvingelectrical circuitry that allows signals to flow, unless statedotherwise, includes an electrical connection and is not necessarily adirect physical connection regardless of whether the word “electrical”is used to modify “connection”.

Elements of different implementations described herein may be combinedto form other embodiments not specifically set forth above. Elements maybe left out of the structures described herein without adverselyaffecting their operation. Furthermore, various separate elements may becombined into one or more individual elements to perform the functionsdescribed herein.

What is claimed is:
 1. A test system comprising: test sites comprisingsockets for testing devices under test (DUTs); pickers for picking DUTsfrom the sockets or placing the DUTs in the sockets; a gantry on whichthe pickers are mounted, the gantry being configured to move the pickersrelative to the test sites to position the pickers for picking the DUTsfrom the sockets or placing the DUTs into the sockets; and one or moreLASER range finders mounted on the gantry for movement over the DUTs inthe sockets and in conjunction with movement of the pickers, a LASERrange finder being configured to detect a distance to a DUT placed intoa socket.
 2. The test system of claim 1, further comprising: a controlsystem to determine a plane of the DUT based on multiple distancesdetected by the LASER range finder, and to determine whether the DUT hasbeen placed properly in the socket based on the plane of the DUT.
 3. Thetest system of claim 2, wherein the control system is configured todetermine whether or not to place a lid over the socket based on whetherthe DUT has been placed properly into the socket.
 4. The test system ofclaim 3, wherein the control system is configured to control movement ofthe lid to be placed over the socket when the DUT has been placedproperly in the socket.
 5. The test system of claim 3, wherein thecontrol system is configured to control the lid not to be placed overthe socket when the DUT has been placed improperly in the socket.
 6. Thetest system of claim 1, wherein the LASER range finder comprises aone-dimensional (1D) LASER range finder.
 7. The test system of claim 1,wherein each LASER range finder is mounted on to a respective picker. 8.The test system of claim 1, wherein the LASER range finder is configuredto detect distances to the DUT placed into the socket in parallel withmovement of the gantry following placement of the DUT into the socket.9. A test system comprising: test sites comprising sockets for testingdevices under test (DUTs); pickers for picking DUTs from the sockets orplacing the DUTs into the sockets; a gantry on which the pickers aremounted, the gantry being configured to move the pickers relative to thesockets to position the pickers for picking the DUTs from the sockets orplacing the DUTs into the sockets; and a scanner configured to face thesockets and to move over the sockets, the scanner being configured tocapture three-dimensional data (3D) representing a structure of at leastpart of a socket.
 10. The test system of claim 9, further comprising: acontrol system to determine a location and an orientation of the socketbased on the 3D data.
 11. The test system of claim 10, wherein thecontrol system is configured to determine a plane of the socket, a rolland pitch of the plane, and a height of the plane relative to a baseholding the sockets.
 12. The test system of claim 11, wherein thecontrol system is configured to determine Cartesian X, Y, and Zcoordinates of the plane and a yaw of the plane.
 13. The test system ofclaim 12, wherein the control system is configured to determine theCartesian X, Y, and Z coordinates of the plane and the yaw of the planebased on features associated with the socket.
 14. The test system ofclaim 10, wherein the control system is configured to control a pickerto place a DUT into the socket based on the location and orientation ofthe socket.
 15. The test system of claim 14, wherein the control systemis configured to control the picker to place the DUT into the socket ata precision measured in single-digit microns.
 16. The test system ofclaim 9, wherein the 3D data comprises a 3D point cloud.
 17. A testsystem comprising: trays comprising cells for holding at least one ofdevices to be tested or devices that have been tested; pickers forpicking the devices to be tested from the trays and for placing thedevices that have been tested into the trays; a gantry on which thepickers are mounted, the gantry being configured to move the pickersrelative to the cells to position the pickers for picking the devices tobe tested or for placing the devices that have been tested; a scannerconfigured for movement over the trays, the scanner being configured tocapture three-dimensional data (3D) representing structures of the traysand presence or absence of devices in at least some of the cells; and acontrol system to determine, based on the 3D data, which of the cellscontains devices and whether devices in the cells are placed properly.18. The test system of claim 17, wherein, for a tray among the trays,the control system is configured to perform a comparison based on 3Ddata for the tray and a predefined model of the model of the tray. 19.The test system of claim 17, wherein, for a tray among the trays, thecontrol system is configured to compare a representation of the traybased on the 3D data to a predefined model of the tray.
 20. The testsystem of claim 17, wherein determining whether a device in a cell isplaced properly comprises determining whether the device in the cell isat a prescribed orientation or with an acceptable tolerance of theprescribed orientation.
 21. The test system of claim 17, wherein the 3Ddata comprises a 3D point cloud.
 22. The test system of claim 17, thescanner comprises a 3D scanner mounted on a linear motorized axis overthe trays.
 23. A test system comprising: test sites comprising socketsfor testing devices under test (DUTs); pickers for picking DUTs from thesockets or placing the DUTs in the sockets; a gantry on which thepickers are mounted, the gantry being configured to move the pickersrelative to the sockets to position the pickers for picking the DUTsfrom the sockets or placing the DUTs into the sockets; a scannerconfigured to face towards a DUT held by a picker controlled to placethe DUT in a socket at a test site, the scanner being configured tocapture three-dimensional data (3D) representing the picker holding theDUT prior to placement of the DUT in the socket; and a control system todetermine, based on the 3D data, whether the DUT is properly orientedfor placement in the socket.
 24. The test system of claim 23, whereinthe scanner comprises a 3D scanner that is oriented to face upwardstoward a bottom of the DUT.
 25. The test system of claim 23, wherein thescanner is a first scanner and the 3D data is first 3D data; wherein thetest system further comprises a second scanner configured for movementover the sockets, the second scanner being configured to capture second3D data representing a structure of at least part of the socket; andwherein the control system is configured to control the picker to placethe DUT into the socket based on the first 3D data and the second 3Ddata.
 26. The test system of claim 25, wherein the control system isconfigured to control the picker to place the DUT into the socket at aprecision measured in single-digit microns.
 27. The test system of claim23, wherein the 3D data comprises Cartesian X, Y, and Z coordinates forthe DUT being held by the picker prior to placement in the socket. 28.The test system of claim 27, wherein the 3D data comprises pitch, yaw,and roll information for the DUT being held by the picker prior toplacement in the socket.
 29. The test system of claim 23, wherein thescanner is fixed in place.
 30. A test system comprising: a strobe light;test sites comprising sockets for testing devices under test (DUTs);pickers for picking DUTs from the sockets or placing the DUTs in thesockets; a gantry on which the pickers are mounted, the gantry beingconfigured to move the pickers relative to the sockets to position thepickers for picking the DUTs from the sockets or placing the DUTs intothe sockets; a camera configured to face towards a DUT held by a pickercontrolled to place the DUT in a socket at the test site, the camerabeing configured to capture an image of the picker holding the DUT priorto placement of the DUT in the socket; and a control system to controloperation of the gantry to reduce a speed of the picker as the pickerapproaches the camera, to control operation of the strobe light and thecamera to capture an image of the picker holding the DUT prior toplacement of the DUT in the socket, and to use the image to determine aposition and an orientation of the DUT relative to the socket.
 31. Thetest system of claim 31, wherein controlling the strobe light and thecamera comprises causing the strobe light to illuminate at a time thatthe camera is controlled to capture the image.
 32. The test system ofclaim 31, wherein the speed of the picker is reduced to a constantspeed.
 33. The test system of claim 30, wherein the test systemcomprises a single camera to capture an image of each picker holding aDUT.
 34. The test system of claim 30, wherein the test system comprisesmultiple cameras, each of the multiple cameras being associated with adifferent test site and being configured to face towards a DUT held by apicker controlled to place the DUT in a socket, each camera beingconfigured to capture an image of the picker holding the DUT prior toplacement of the DUT in a socket of the different test site.
 35. A testsystem comprising: test sites comprising sockets for testing devicesunder test (DUTs); pickers for picking DUTs from the sockets or placingthe DUTs in the sockets; a gantry on which the pickers are mounted, thegantry being configured to move the pickers relative to the test sitesto position the pickers for picking the DUTs from the sockets or placingthe DUTs into the sockets; a camera configured for positioning over asocket using servo control to capture an image of the socket or of adevice in the socket; and a control system to implement the servocontrol of the camera and to use the image to control placing the DUT inthe socket or picking the DUT from the socket.
 36. The test system ofclaim 35, wherein the camera is a three-dimensional (3D) camera tocapture 3D image data representing at least the socket.
 37. The testsystem of claim 36, wherein the 3D camera comprises an imaging devicecomprised of two or more lenses that enables perception of depth incaptured images to produce a 3D image.
 38. The test system of claim 36,wherein the 3D camera comprises a two-dimensional (2D) camera to capture2D data of at least the socket and a pointing laser to capture a thirddimension of data for at least the socket, the 2D data and the thirddimension of the data being the 3D image data.